Vladimir Putin responded to President Trump slapping sanctions on Russia's two biggest oil companies in a U.S. policy shift over the war in Ukraine.

They know we have a nuclear submarine, the greatest in the world, right off their shore,” President Trump said.

The main reason that no one else has tried to build something like this is that it doesn’t really have any use," one expert told NBC News.

The Army is overhauling how it fights in combat based on lessons from Russia's invasion of Ukraine, where drones have become the dominant weapon on the battlefield.

Russian President Vladimir Putin's special envoy for investment and economic cooperation said he believes the United States, Ukraine, and Russia are close to a diplomatic solution to end the war in Ukraine.

The U.S. sent fighter jets, yet again, to identify and intercept Russian military aircraft in the Alaskan Air Defense Identification Zone.

Russia, by contrast, stands to lose the most. Syria canceled an Assad-era contract with Russia to manage Tartus naval base but Syria's defense minister also said it might let Russia keep this port and the Hmeimim airbase "if we get benefits for Syria."

Zelenskyy was in London for talks with two dozen European leaders who have pledged military support to shield his country from future Russian aggression.View on euronews

The 10,000 U.S. troops now operating in the Caribbean were sent to interdict drug boats. But Venezuelan President Nicolás Maduro's Sept. 30 state of external emergency fundamentally changed what they're facing: a military on full wartime alert,

Ukrainian President Volodymyr Zelenskyy is set to meet European leaders in London on Friday. They have pledged military support to protect Ukraine from future Russian aggression if a ceasefire occurs.

Finland will provide four new icebreakers to America under a $6.1 billion agreement as the U.S. seeks to strengthen Arctic defense against Russia and China.

While it is not clear whether Washington will actually carry out any of those moves in the immediate term, it shows there is a well-developed toolkit within the administration to up the ante further after Trump imposed sanctions on Russia on Wednesday for the first time since returning to office in January.