Russia has laughed off a US warship's “challenge” to its territorial claims in the Sea of Japan as “unsuccessful” while reacting angrily to reports that US ships could also enter the Black Sea.
The US naval activity comes less than two weeks after Russia seized three Ukrainian ships off the coast of Crimea in the Black Sea last month in an escalation of existing tensions there.
The guided missile destroyer USS McCampbell “sailed in the vicinity of Peter the Great Bay to challenge Russia's excessive maritime claims” in a demonstrative “freedom of navigation” operation on Wednesday, the navy said.
But the Russian defence ministry claimed on Thursday that the McCampbell had not come closer than 100 kilometres (62 miles) to its territorial waters and was currently “demonstrating its bravery” 250 miles from Russian shores.
A destroyer and several warplanes nonetheless followed the US ship, which tried to “get away at maximum speed,” the ministry said in a sarcastic statement carried on state television.
Moscow has since Soviet times maintained that the entire Peter the Great Bay, which includes the home base of its Pacific fleet in Vladivostok, is historically Russian territory.
Washington on the other hand argues that Russian waters extend only 12 nautical miles from shore as per international law.
In an unrelated incident, five marines were missing after an American fighter jet collided with a tanker plane during refuelling over the Sea of Japan on Thursday.
The navy's freedom of navigation operation marked a geographical broadening of tensions between Russia and the US, which has previously focused on challenging Chinese claims in the South China Sea, most recently sailing naval ships near contested areas there last week.
The two Cold War foes are also at odds over a landmark arms control treaty that Donald Trump wants to abandon. Vladimir Putin, the Russian president, said on Wednesday Russia would develop new missiles if the US withdrew.
Meanwhile, CNN reported that the US was notifying Turkey of “possible plans” to sail a warship into the Black Sea in response to the capture of three Ukrainian ships and 24 sailors there on November 25.
The ships were headed for Ukrainian ports in the Sea of Azov through the Kerch Strait, which has been controlled by Russia since the 2014 annexation of Crimea.
US senator John Barrasso had called on Sunday for American and Nato ships to be sent to the Black Sea in a show of force against Russia.
The purported plan provoked a blustery response from Russian politicians and pundits on Thursday, with one warning Russia could repeat the incident of February 1988, when a Soviet frigate rammed a US cruiser in the Black Sea.
MP Yury Shvytkin vowed that Russia would “respond accordingly” if Russia's waters were violated.
“I wouldn't really want our submarines to have to surface off the American coast,” he said.
Following the seizure of its ships, Kiev has declared martial law and called up reservists in response to claims of a Russian troop buildup on its borders, which Moscow has denied.
On Thursday, parliament moved forward on legislation claiming Ukraine's waters extend 24 nautical miles into the Black Sea.
In a New York Times editorial on Wednesday, Ukrainian president Petro Poroshenko told Western leaders to stop “appeasing” Mr Putin and adopt further sanctions on Russia in response to its “unprovoked military attack”.
The head of the Ukrainian fleet has offered himself in exchange for the 24 captured sailors, who face six years in prison on charges of violating Russia's borders. The Russian foreign ministry retorted that he should resign instead.