A Russian fighter jet zoomed within just 10 feet of a U.S. Navy spy plane over the Black Sea on Wednesday, the latest in a string of daring maneuvers involving Russian aircraft and the U.S. military, a defense official with knowledge of the incident told Fox News.

The Russian Su-27 Flanker jet flew dangerously close to a U.S. Navy P-8 Poseidon reconnaissance aircraft used primarily for anti-submarine warfare while on routine patrol in international airspace, defense officials said.

The Russian defense ministry accused the Navy plane of flying with its transponder—which emits an identifying signal—turned off. A U.S. defense official would neither confirm nor deny the accusation but told Fox News, "It is not a requirement for a military aircraft to have its transponder turned on."

The official said Russian military jets routinely fly with their transponders turned off, which helps the U.S. military identify them because other planes in the area are emitting an identifying signal from their transponders. The Navy spy plane was roughly 40 miles from Russia in the Black Sea when the Russian jet approached, according to a separate defense official.

Fox News is told a classified photo of the close call exists, but officials have not decided whether to release it. The entire encounter lasted 19 minutes, according to the Pentagon.

"We have concerns when there is an unsafe maneuver like this. These actions have the potential to unnecessarily escalate tensions, and could result in a miscalculation or accident," Navy Captain Jeff A. Davis told reporters. Russian defense officials reportedly claimed they did not violate any international rules.

The Black Sea is about 500 miles south of Moscow.

In April, Russian jets buzzed a U.S. Navy destroyer in the Baltic Sea, coming within 30 feet of the Navy ship.

Photos and video also showed a series of provocative moves from Iran's powerful Revolutionary Guard targeting the U.S. military.

On Sunday, the Guard's fast-attack boats came within some 500 yards of the USS Firebolt, with one stopping right in front of the coastal patrol boat in the Persian Gulf, said Cmdr. Bill Urban, a spokesman for the U.S. Navy's 5th Fleet, based in Bahrain. Urban said the USS Firebolt turned and missed the boat by only about 100 yards. Iranian speedboats fired rockets near U.S. warships and commercial traffic in December, and an Iranian drone overflew an American aircraft carrier in January. 

This latest Russian provocation comes as Secretary of State John Kerry is negotiating a cease-fire with Russia in Syria. Shortly after the spy plane encounter, Secretary of Defense Ash Carter said Russian officials were "trying to play by their own rules" and making the situation in Syria "more violent."

Carter added, "Russia's actions in recent years - with its violations of Ukrainian and Georgian territorial integrity, its unprofessional behavior in the air, in space, and in cyber-space, as well as its nuclear saber-rattling - all have demonstrated that Russia has clear ambition to erode the principled international order."

Carter was speaking at Oxford University in the United Kingdom.

Fox News' Lucas Tomlinson and The Associated Press contributed to this report.