Ukraine–Russia War: Probability of Ending Before October 1, 2026

Updated September 13, 2026

Event Definition

The event resolves positively if, before October 1, 2026, one of the following occurs:

Russia and Ukraine sign a peace treaty, armistice, or other qualifying written agreement that ends the war;
Russia annexes all or most of Ukraine; or
Ukraine wins the war in a manner that changes the authorities governing the Kremlin.

A temporary humanitarian pause, a limited exchange of prisoners, a diplomatic meeting, a political declaration, or an agreement to continue negotiations would not normally qualify unless it clearly constitutes a written, war-ending agreement.

As of September 13, 2026, there are 18 calendar days from September 13 through September 30, inclusive, before the October 1 resolution date. The practical negotiating window is therefore extremely short.

1. Executive Forecast

Estimated probability of a qualifying event before October 1, 2026: approximately 0.4–0.9%

My central estimate is now approximately 0.6%, lower than the previous estimate of roughly 1%.

The diplomatic channel remains open, but developments since the previous assessment have been predominantly negative for a near-term settlement:

Ukrainian officials now describe a possible next round of U.S.–Ukraine–Russia talks as more likely to occur in October, after the September 20 Russian elections.
Russian Foreign Minister Sergey Lavrov said on September 12 that Russia is willing to negotiate but would not stop fighting during the negotiations.
The Kremlin has rejected or dismissed proposals for a mutual pause in aerial attacks, including attacks on energy infrastructure.
Russia conducted further large-scale strikes on Ukraine, including attacks that reportedly killed at least eight civilians on September 12.
Zelenskyy continues to reject territorial concessions and argues that a temporary lull without reliable security guarantees would merely postpone another war.
The United States remains actively engaged, but the September 5–8 diplomatic contacts produced no publicly announced ceasefire framework, territorial formula, monitoring mechanism, or signing timetable.

There are still modest positive indicators. Zelenskyy has said that initial results from the diplomatic process could emerge by the end of September, and he has expressed willingness to meet Vladimir Putin in person at a later summit. President Donald Trump continues to say that Putin wants a deal. However, these statements concern the continuation or reopening of negotiations rather than an agreement likely to end the war before October 1. (en.interfax.com.ua)

Updated probability table

Outcome before October 1, 2026	Estimated probability
Qualifying peace treaty, armistice, or war-ending written agreement	0.4–0.9%
Russian annexation of all or most of Ukraine	Far below 0.1%
Ukrainian victory involving a change in Kremlin authorities	Far below 0.1%
War continues without a qualifying settlement	Approximately 99.1–99.6%

The only realistic positive pathway is a hastily negotiated written armistice that freezes the front and defers territorial questions. The newest evidence indicates that even the next substantive trilateral talks may not occur until October, after the resolution deadline.

2. Developments Since the September 11 Assessment

2.1 Ukrainian officials now anticipate talks in October

The most important new development is that Kyrylo Budanov, a senior Ukrainian official involved in the diplomatic process, said that the next U.S.–Ukraine–Russia talks may take place in October. Reuters reported that Kyiv was preparing for a possible resumption of three-sided talks after the September 20 Russian elections. (kyivindependent.com)

This materially reduces the probability of resolution before October 1. A process that begins in October cannot itself satisfy the event unless a qualifying agreement is signed before the deadline. Even if the parties held preliminary contacts in late September, the available period would be insufficient for a normal negotiation over territory, security guarantees, sanctions, force positions, monitoring, implementation, and enforcement.

Budanov’s reported expectation also contrasts with earlier public optimism that the United Nations General Assembly period might produce immediate progress. The diplomatic process appears to be moving toward a later round of talks rather than an imminent settlement.

2.2 Russia rejects a pause in fighting during negotiations

On September 12, Lavrov said that Russia remained prepared to negotiate but would not suspend its military operations while talks were taking place. The statement directly weakens the possibility of a rapid armistice because it indicates that Moscow does not view a ceasefire as a prerequisite for diplomacy. (kyivindependent.com)

A written agreement ending the war could theoretically be signed without a prior ceasefire. However, continued Russian attacks during negotiations would make it much harder for Ukraine to accept an agreement and would undermine confidence in any proposed monitoring or enforcement mechanism.

This position is consistent with the Kremlin’s earlier rejection of a proposed pause in aerial attacks and its insistence that Ukraine must offer terms aligned with Russian interests rather than merely seek a limited truce. (kyivindependent.com)

2.3 Russia continues large-scale attacks

Russian forces conducted substantial attacks on September 12. The Associated Press reported that Russian strikes killed eight civilians and wounded dozens of others, while Putin warned that the deployment of European troops to Ukraine would constitute direct conflict with Russia. (apnews.com)

The continuation of major attacks while diplomatic contacts are being discussed is a strong negative indicator. It suggests that Russia is using military pressure to improve its position rather than preparing to freeze the current battlefield.

The attacks also appear inconsistent with the idea that the September 5–6 pause around the visits by Witkoff and Kushner represented the beginning of a broader cessation. No nationwide ceasefire has followed.

2.4 Zelenskyy remains open to diplomacy but rejects territorial concessions

Zelenskyy has continued to say that Ukraine is pursuing peace and that initial diplomatic results could emerge by the end of September. At the same time, he has stated that Ukraine will not trade its territory for a temporary lull and that concessions could merely postpone a larger future Russian attack. (en.interfax.com.ua)

This leaves open the possibility of an armistice that freezes the front without resolving sovereignty. However, it makes a settlement involving Ukrainian recognition of Russian territorial claims highly unlikely within the remaining time.

The Ukrainian position also emphasizes continued air defense, domestic military capacity, European and North American partnerships, and security guarantees extending beyond the immediate war. These priorities point toward a durable postwar security arrangement rather than a quick ceasefire with minimal guarantees. (president.gov.ua)

2.5 Zelenskyy offers to meet Putin at a future G20 summit

Zelenskyy said on September 12 that he was prepared to meet Putin at the G20 summit scheduled for December in Miami. This is evidence that Kyiv is not categorically rejecting a leader-level meeting. However, the proposed date is well after the October 1 deadline and therefore has no direct positive effect on the event. (kyivindependent.com)

The offer may indicate that Ukraine sees a future presidential meeting as possible under suitable conditions. It also reinforces the conclusion that the parties do not currently expect a leader-level peace meeting during the narrow period before October 1.

3. Status of the Diplomatic Process

U.S.–Russia contact

Trump spoke with Putin on September 8 and publicly characterized the discussion as positive. Trump said Putin wanted to make a deal, while also identifying the hostility between Putin and Zelenskyy as a principal obstacle. Russian accounts said the conversation addressed the outcome of the Witkoff–Kushner meetings and the possibility of renewed negotiations. (cbsnews.com)

The call is a positive indicator only in the narrow sense that senior-level communication remains active. No public agreement emerged on:

a ceasefire;
the territorial line;
Ukrainian security guarantees;
sanctions relief;
Russian force withdrawals;
monitoring;
prisoner exchanges;
reconstruction; or
a date for a formal summit.

Trump’s public statements therefore appear to reflect political intent and optimism rather than a completed negotiating framework.

U.S.–Ukraine coordination

Witkoff and Kushner met Putin in Moscow on September 5 and Zelenskyy in Kyiv on September 6. The meetings were described as constructive and were intended to revive a diplomatic channel that had lost momentum. The envoys reportedly brought new ideas for restarting negotiations and explored winter de-escalation measures. (apnews.com)

Nevertheless, no draft armistice or joint framework was announced. The process appears to have produced exploratory discussions rather than commitments that could be converted into a war-ending agreement within eighteen days.

Prospective post-election diplomacy

The September 20 Russian parliamentary elections appear to be a major timing constraint. Zelenskyy has said that meaningful negotiations are unlikely during the electoral period, while Ukrainian officials now point toward late September or October for renewed trilateral discussions. (en.interfax.com.ua)

If talks begin only after September 20, the parties would have approximately ten days or fewer before the deadline. That is theoretically sufficient for a politically imposed ceasefire but not for a conventional peace process. The forecast therefore depends almost entirely on whether the leaders can impose a short written armistice without resolving the underlying issues.

4. Evidence Supporting a Positive Resolution

4.1 Continued high-level U.S. involvement

Trump remains personally involved and continues to communicate with Putin and Zelenskyy. The United States has also dispatched senior envoys to both Moscow and Kyiv. A presidential decision could theoretically produce an agreement more quickly than a standard diplomatic process. (cbsnews.com)

4.2 Russia has not formally closed the diplomatic channel

The Kremlin has said it does not rule out resuming trilateral talks. This keeps the probability above zero and indicates that Russia may still see value in negotiations with the United States and Ukraine. (rte.ie)

4.3 An interim armistice could defer territorial questions

A qualifying document would not necessarily need to settle the permanent legal status of every occupied territory. A sufficiently broad and clearly war-ending armistice could potentially:

halt nationwide attacks;
freeze forces along the existing line of contact;
establish international monitoring;
provide for prisoner exchanges;
protect energy and civilian infrastructure;
defer sovereignty questions; and
commit the parties to later negotiations.

This remains the most plausible positive scenario. It is also the only scenario compatible with the limited time available.

4.4 Late-September political pressure

The UN General Assembly, the Russian elections, the approaching winter, and continued U.S. pressure could create incentives for the parties to announce at least an interim arrangement before October 1. Zelenskyy’s statement that initial diplomatic results could appear by the end of September provides some support for retaining a small probability of a last-minute agreement. (en.interfax.com.ua)

However, “initial results” could mean resumed talks, a framework, or a limited humanitarian arrangement rather than an agreement that ends the war. The statement should therefore not be treated as evidence of a likely qualifying settlement.

5. Evidence Against a Positive Resolution

5.1 The next substantive talks may occur after the deadline

The clearest negative indicator is the reported expectation that the next trilateral talks may take place in October. This would place the principal negotiating event after the resolution date. (kyivindependent.com)

5.2 Russia rejects a ceasefire during negotiations

Lavrov’s September 12 statement that Russia will continue fighting while negotiations proceed directly conflicts with the type of immediate nationwide armistice most likely to qualify. (kyivindependent.com)

5.3 No energy or aerial truce has been achieved

The Kremlin has dismissed a U.S.-backed proposal for a mutual pause in aerial strikes and has described Ukraine’s approach as a limited truce rather than a permanent settlement. This is important because a sectoral agreement would normally be easier to reach than a nationwide armistice. (kyivindependent.com)

If Russia and Ukraine cannot agree even on a narrow energy or aerial pause, a comprehensive written cessation of hostilities within the remaining period is unlikely.

5.4 Major attacks continue

The September 12 strikes, including civilian deaths and large-scale drone and missile activity, show that military operations remain intense. (apnews.com)

There is no observable pattern of sustained de-escalation. Instead, diplomacy and military pressure are occurring simultaneously.

5.5 Russia and Ukraine remain far apart on the central political questions

The principal unresolved issues remain:

whether Russia may retain occupied Ukrainian territory;
whether Ukraine must formally or informally recognize territorial changes;
whether Russian forces must withdraw;
what security guarantees Ukraine would receive;
whether Ukraine could maintain its current military capabilities;
how sanctions would be lifted or restored;
how violations would be verified and punished; and
whether a ceasefire would be temporary or permanent.

Ukraine’s public rejection of territorial concessions and Russia’s insistence on terms aligned with its strategic objectives indicate that the parties remain far apart. (kyivindependent.com)

5.6 Allied preparations point toward a continuing war

Canada and Ukraine recently deepened defense and military-industrial cooperation, including air defense, drones, ammunition, energy security, and support extending through 2029. Zelenskyy has also emphasized that Ukraine must strengthen its own military capabilities for both the war and the postwar period. (president.gov.ua)

These steps do not prove that diplomacy will fail, but they are more consistent with planning for a prolonged conflict than with an imminent settlement.

5.7 The timeline is too short for a conventional peace process

Even if trilateral talks began immediately after the Russian elections, the parties would need to resolve or defer:

the line of contact;
territorial status;
security guarantees;
sanctions;
military withdrawals;
monitoring;
prisoner and civilian issues;
reconstruction;
enforcement; and
ratification or implementation.

A public commitment to continue negotiations would not ordinarily qualify. A draft agreement without signatures would not qualify. A limited humanitarian or energy arrangement may also fail to qualify unless it clearly ends active hostilities.

6. Scenario Analysis

Scenario A: Last-minute written armistice after September 20

Estimated probability: 0.4–0.9%

After the Russian elections, Trump or his envoys persuade Putin and Zelenskyy to sign a short armistice. The document freezes the front, halts nationwide attacks, establishes monitoring, and postpones final territorial questions.

This remains the only credible positive pathway. It is supported by continued U.S. engagement and Zelenskyy’s statement that initial results could emerge by the end of September. It is unlikely because Russian officials reject a pause during negotiations, attacks continue, and Ukrainian officials increasingly anticipate talks in October.

Scenario B: Late-September contacts without a settlement

Estimated probability: 15–25%

The United States, Ukraine, and Russia hold indirect or preliminary contacts before October 1. They discuss energy, winter de-escalation, prisoners, or the architecture of future negotiations but sign no war-ending agreement.

This is more likely than a qualifying settlement. The parties may seek a diplomatic announcement without being prepared to stop military operations.

Scenario C: Limited sectoral or humanitarian agreement

Estimated probability: 2–5%

The parties agree to protect energy infrastructure, facilitate grain shipments, exchange prisoners, or pause attacks in a limited area.

This scenario is possible but has diminished in probability because the Kremlin has rejected or dismissed an aerial or energy truce. Moreover, a narrow agreement would not necessarily satisfy the event’s resolution rules. It would qualify only if it clearly constituted a written agreement ending the war or creating a sufficiently broad armistice.

Scenario D: Continued fighting with diplomacy deferred to October

Estimated probability: 70–80%

Russia and Ukraine continue military operations through September 30. The United States maintains diplomatic contacts, while the next serious trilateral discussions occur in October.

This is now the clear base case. It is supported by the reported October timing for future talks, Russia’s refusal to suspend operations during negotiations, continued attacks, unresolved territorial disputes, and Ukraine’s ongoing defense preparations. (kyivindependent.com)

Scenario E: Decisive military or political collapse

Estimated probability: far below 0.1%

This includes Russia annexing all or most of Ukraine, the Ukrainian state collapsing, or Ukraine winning in a manner that changes the authorities governing the Kremlin.

There is no credible evidence that either outcome could occur before October 1, 2026.

7. Indicators That Would Materially Increase the Forecast

The probability should rise sharply if any of the following occur:

Russia and Ukraine announce a nationwide ceasefire.
Putin agrees to meet Zelenskyy before September 30.
A formal Trump–Putin–Zelenskyy summit is scheduled before the deadline.
Russia accepts negotiations based on the current line of contact.
Russia agrees to defer territorial-status questions.
Moscow and Kyiv issue a joint statement describing the same ceasefire framework.
A draft armistice is publicly released.
The United States announces specific and enforceable security guarantees.
A monitoring and enforcement mechanism is agreed.
Russian missile and drone attacks decline sharply for several consecutive days.
Russia orders a verifiable halt to attacks on Ukrainian cities and infrastructure.
The parties sign an energy or aerial truce that explicitly links to a broader cessation of hostilities.
Russian officials shift from military objectives toward implementing a ceasefire.
A late-September meeting is announced with a specific mandate to finalize an armistice.

The forecast should fall below 0.5% if:

no meeting is scheduled before September 30;
the UN General Assembly period produces no concrete framework;
Russia continues major attacks after further diplomatic contacts;
Moscow reiterates maximal territorial demands;
Kyiv rejects proposals requiring territorial concessions;
Russia continues rejecting even limited infrastructure truces; or
Ukrainian or Russian authorities announce a major offensive, mobilization, or escalation.

8. Final Assessment

The diplomatic process remains active but has not produced a settlement mechanism. The September 5–8 U.S. diplomatic contacts reopened communication, yet there is still no announced ceasefire, armistice text, territorial framework, monitoring plan, or implementation schedule. Trump’s positive statements and Russia’s willingness to discuss future talks provide some residual probability of a last-minute agreement, but they do not demonstrate that either side is ready to end the war.

The newest developments are more negative. Ukrainian officials now anticipate that the next trilateral talks may take place in October, while Lavrov has said Russia will continue fighting during negotiations. Russia has rejected or dismissed an aerial or energy truce, and large-scale attacks continued on September 12, killing civilians. Ukraine remains willing to negotiate but continues to reject territorial concessions and emphasizes long-term defense and security guarantees. (kyivindependent.com)

A qualifying event before October 1 would therefore require an extraordinary last-minute political decision, most likely a written interim armistice imposed or brokered by the United States after the September 20 Russian elections. That possibility is not zero, but the remaining timeframe and the parties’ current positions make it highly unlikely.

Final forecast

Estimated probability that the Ukraine–Russia war ends through a qualifying peace treaty, armistice, settlement, Russian annexation of Ukraine, or Ukrainian victory involving a change in Kremlin authorities before October 1, 2026: approximately 0.4–0.9%, with a central estimate near 0.6%.

The most likely outcome is that the war continues beyond October 1, 2026, with diplomatic activity either continuing in late September without a settlement or shifting into a more substantive U.S.–Ukraine–Russia process during October. A limited ceasefire is more plausible than a comprehensive peace treaty, but Russia’s refusal to pause attacks during negotiations makes even that outcome unlikely within the resolution window.

Source Document for Event 2 (13-09-2026)