Russian border guards seized the Ukrainian military ships during a provocation in the Kerch Strait on November 25, 2018.
There are two scenarios of the US launching war against Russia. The first envisages a US military attack using all available means, including nuclear weapons. The second scenario envisages Russia’s economic isolation in order to induce a “change of political leadership”. The likelihood of combat action is quite real, as Washington may urgently need a “fairly large war”.
This claim involves speculation without evidence. It is a recurring pro-Kremlin disinformation narrative about Russophobia, US/NATO military aggression towards Russia, and alleged US funding of "colour revolutions" in Russia and other post-Soviet states. It also plays into the oft-used narrative that the West wants to conquer and subdue Russia, in order to portray Russia as the victim of unjustified aggression against which it must defend itself. For similar cases about US and NATO warmongering towards Russia and its neighbours, see here.