A Russian Su-27 fighter jet intercepted a US surveillance plane over the Black Sea on Monday, prompting the American government to protest the manoeuvre as "an unsafe interaction".
The US State Department said the Russian jet closed to within five feet and crossed directly in front of the EP-3 Aries II plane.
The encounter, first reported by Russia's RIA news agency, cited the defence ministry as saying the US Navy aircraft, did not violate Russian air space.
"This is but the latest example of Russian military activities disregarding international norms and agreements," said the State Department.
"We call on Russia to cease these unsafe actions that increase the risk of miscalculation, danger to aircrew on both sides, and midair collisions."
MT @USNavyEurope : #USNavy EP-3 Aries flying in international airspace over #BlackSea was intercepted by Russian Su-27. Interaction determined unsafe: Su-27 came within 5 feet & crossed thru EP-3’s flight path, causing EP-3 to fly thru Su-27 jet wash. [File Photo] pic.twitter.com/B25rRhpeyU
— U.S. Navy (@USNavy) January 29, 2018
Moscow said that "all security precautions" had been observed during the encounter.
"After the surveillance plane of the US Navy had changed its course to move away from the border, the Su-27 returned to its base," RIA quoted the Russian defence ministry as saying.
Russian jets and Nato aircraft have frequently come close together over the Black Sea, the Baltic region, Syria and elsewhere.
Images released by US European Command last yearshow a Russian SU-27 flying close to the wing of a US RC-135U. The planes are so close that the Russian pilot can be seen in the cockpit.