The U.S. Navy accused a Russian ship of “unsafe and unprofessional” conduct after an incident Friday in the Philippine Sea caused a near-collision between a Russian destroyer and the American guided missile cruiser USS Chancellorsville.

The Russian Pacific Fleet countered that it was the U.S. vessel that had engaged in dangerous maneuvering, forcing the Russian destroyer Admiral Vinogradov to take emergency action, Russia’s Interfax news agency reported.

According to Cmdr. Clay Doss of the U.S. 7th Fleet, the Chancellorsville was recovering its helicopter while maintaining a steady course when the Russian ship came from behind and “accelerated and closed to an unsafe distance” of about 50 to 100 feet.

“This unsafe action forced Chancellorsville to execute all engines back full and to maneuver to avoid collision,” Doss said in a statement. “We consider Russia’s actions during this interaction as unsafe and unprofessional.”

The Russian statement, however, said the U.S. cruiser “suddenly changed directions and came within 50 meters [164 feet] of the Russian destroyer.” Russia, which stated that the incident took place in the East China Sea, said its ship was forced to perform an emergency maneuver and warned the American ship of inadmissible actions.

Speaking outside the Pentagon on Friday, acting defense secretary Patrick Shanahan said the United States planned to issue a formal diplomatic protest to Russia. 

“The behavior is unsafe and unprofessional,” Shanahan said. “We’ll have military-to-military conversations with the Russians, and of course, we will démarche them. To me, safety at the end of the day is the most important. It will not deter us from conducting our operations.”

Since January 2018, the Pentagon has been implementing a new long-term strategy that refocuses the U.S. military on competition with Russia and China, which have both been building up and modernizing their militaries and challenging the once unquestioned naval supremacy of the United States.

Russia’s Pacific Fleet, based in Russia’s port city of Vladivostok, regularly takes part in joint naval exercises with China in Pacific waters. The last exercise, which involved the Admiral Vinogradov destroyer, wrapped up in early May after live-fire drills.

The exercises marked the second time Russian vessels had docked in the Philippines this year. But it was not immediately clear why the Admiral Vinogradov was in the Philippine Sea near the U.S. vessel.

Russia and the Philippines — a longtime U.S. ally — are expected next month to finalize an agreement on naval cooperation, according to Chinese state media reports.

The incident comes as the U.S. military feels increasing pressure on the Pacific seas, where China for years has been militarizing artificial islands to assert influence over the South China Sea and expanding air defenses over the East China Sea.

It was the second close brush between Russian and U.S. forces this week. On Tuesday, the Navy’s 6th Fleet said a Russian Su-35 fighter plane flew “directly in front” of a U.S. Navy P-8A Poseidon over the eastern Mediterranean. There were no injuries or harm to the planes, but the Navy called the Russian interception an “irresponsible” action that “put our pilots and crew at risk.”

Adm. John Richardson, U.S. chief of naval operations, said Friday that the behavior by the Russian destroyer’s captain was irresponsible and reckless. 

“This unwise maneuver, combined with the unsafe maneuvers by Russian aircraft in the eastern Mediterranean earlier this week, make it clear that these dangerous actions by Russian military forces across the globe do not match what the world expects from a responsible and trustworthy world power,” Richardson said in a statement. “The U.S. Navy will not be deterred from supporting the free and open use of the seas and skies where international law clearly allows all to operate.”

The incident Friday is not the first time American and Russian ships have had close calls on the seas as a result of what current and former U.S. officials describe as aggressive and risky maneuvers by the Russian fleet.

The Russian anti-submarine ship Admiral Vinogradov, left, sails close to the USS Chancellorsville on Friday. (Christopher J Krucke/AFP/Getty Images)

In 2016, in the Mediterranean Sea, a Russian frigate came close to a ship from the Dwight D. Eisenhower carrier strike group, which at the time was engaged in striking Islamic State targets in Syria. Another Russian warship also made an erratic maneuver aimed at a U.S. vessel in the carrier strike group days later. Those interactions came amid tensions between the United States and Russia over the conflict in Syria.

American and Russian aircraft regularly intercept one another, and the Pentagon often accuses the Russian military of unsafe behavior when those actions occur. 

On the seas, fleets belonging to Russia and NATO regularly trade barbs over what each side says are infringements on their course in international waters — although they usually take place on the other side of the globe from the Pacific.

In October, a Chinese destroyer came within yards of a U.S. Navy ship conducting “freedom of navigation” missions near disputed islands claimed by China but not recognized as Chinese territory by the rest of the world. The USS Decatur was forced to change course to avoid a collision.

China has described the presence of U.S. ships in these areas as a threat to its sovereignty.

What is somewhat unusual about Friday’s episode is that it didn’t occur anywhere near Russia’s border, according to Jeffrey Edmonds, a research scientist at the nonprofit CNA and a former CIA military analyst and director for Russia on the White House National Security Council.

Edmonds said Russia often engages in aggressive military maneuvers when U.S. vessels or aircraft come close to the Russian border or Moscow’s perceived sphere of influence, essentially issuing warnings to stay away. But the Philippine Sea is far from Russia, he noted, making Friday’s incident a more unusual occurrence. 

He said it is possible that the U.S. vessel was just a “target of opportunity” for the Russian ship — one that happened to be close enough for the Russian vessel to divert. He said he did not think the Russian ship was sent out to find a U.S. cruiser and perform some dangerous action.

More broadly, Edmonds said, the action is part of a pattern of activity in which the Russian military often does something risky to get the attention of the United States, force a conversation or gain recognition of its global reach.  

“They have consistently had this behavior to just try to get in the way to be noticed,” Edmonds said. “It’s to create a problem and then offer to fix it, or create a problem and try to make it look like it’s our fault. But in a sense it’s kind of a great power temper tantrum.”

Edmonds also rejected the idea that the U.S. ship was responsible for the incident, saying a Navy captain would be dismissed on the spot for engaging in such risky behavior, particularly after the recent collisions of the USS John S. McCain and the USS Fitzgerald in the Pacific. 

The incident comes as Russia is hosting Chinese President Xi Jinping and a massive business delegation at a glitzy economic forum in St. Petersburg.

The leaders of the two countries have been heaping praise on each other, with Xi calling President Vladi­mir Putin his “best and bosom” friend.

Both Russia and China are in economic battles with the United States involving sanctions and tariffs.

Amie Ferris-Rotman in Moscow contributed to this report.