Ukraine could receive security guarantees modeled on NATO’s Article 5 mutual defense pledge under a proposed peace deal with Russia, U.S. officials said on Monday — an unprecedented offer aimed at ending the war sparked by Moscow’s 2022 invasion.

Two U.S. officials who spoke on the condition of anonymity said the arrangement would be similar to the NATO mutual defense agreement. But crucial details remain unsettled as negotiators seek a deal that Russia will approve.

The head of Britain’s MI6 spy agency says Russian President Vladimir Putin is stalling efforts to end Russia’s war on Ukraine, and is testing the West with tactics that fall “just below the threshold of war.

Oil prices fell in early trading on Tuesday, adding to the previous session's losses, as prospects for a Russia-Ukraine peace deal appeared to strengthen, raising expectations of a potential easing of sanctions.

The U.S. has agreed to provide unspecified security guarantees to Ukraine as part of a peace deal to end Russia's nearly four-year war, and more talks are likely this weekend, U.S. officials said Monday following the latest discussions with Ukrainian President Volodymyr Zelenskyy in Berlin.

Ukrainian President Volodymyr Zelenskyy said that Ukrainian, U.S. and European officials will hold a series of meetings.

British Prime Minister Keir Starmer and European Commission President Ursula von der Leyen held talks on Saturday on US-led peace efforts for Ukraine and the possible use of frozen Russian assets to support Kyiv,