That the two countries’ top defence and military leaders were talking so soon after the encounter over the Black Sea underscored its seriousness.

The U.S. European Command released dramatic photos of a Russian jet coming within a few feet of a U.S. Air Force reconnaissance jet over the Baltic Sea in a maneuver that has been criticized as unsafe.

Multiple Russian military aircraft came close to a U.S. Navy destroyer in the Black Sea on Feb. 10, incidents considered "unsafe and unprofessional," a U.S. official said on Tuesday.