Russian Deputy Foreign Minister Sergey Ryabkov told ABC News during an exclusive interview in Moscow on Monday that he believes the warring parties are close to a deal.

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.

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 Kremlin has described Ukraine’s push to join NATO as one of the “root causes” of the conflict. U.S. President Donald Trump has ruled out Ukrainian membership in the Western defensive alliance. Zelensky is searching for compromises that could secure a peace deal to end Russia’s ongoing invasion.

A 1,000-strong "dark fleet" of rogue tankers evading sanctions has become a new target for the U.S. and Ukraine, according to a senior maritime intelligence analyst.

While US officials talked up progress in Berlin, there was little detail on how the issue of Ukraine's sovereignty would be resolved.

The Russian submarine was allegedly carrying Kalibr cruise missiles, which Russia has used in devastating strikes on critical infrastructure and military targets across Ukraine. The SBU said the submarine was “put out of action” as a result of the blast. The FT could not independently verify the claim.

Ukraine has relinquished its ambition of joining the NATO military alliance in exchange for Western security guarantees as a compromise to end the war with Russia, President Volodymyr Zelenskyy said ahead of talks with U.S. envoys in Berlin.