Cutting off communication channels. Moving in warships.
Russia reacted to U.S. military strikes on its ally Syria Friday by cutting a hotline intended to prevent midair incidents, a response that demonstrates Moscow's readiness to defy Washington and could even put the two nuclear superpowers on a course toward military confrontation.
President Vladimir Putin signaled he was ready to risk a clash with the U.S. and abandon hopes for mending ties with the U.S. under President Donald Trump, rather than accept the humiliation of standing by while his ally is bombed....
https://www.yahoo.com/news/russia-ups-ante-freezing-communications-us-syria-131416324.html