(CNN)The US Navy sailed three destroyers into the Barents Sea off Russia's Arctic coast Monday, the first time Navy ships have operated in the area since the mid-1980s, the height of the Cold War.
The purpose of the operation was "to assert freedom of navigation and demonstrate seamless integration among allies," US Naval Forces Europe said in a statement.
The three destroyers -- USS Donald Cook, USS Porter and USS Roosevelt -- were joined by a UK Royal Navy frigate, HMS Kent.
The Barents Sea is part of the Arctic Ocean and borders northern Norway and Russia. The Russian port of Murmansk, which hosts the Russian Navy's Northern Fleet, sits on the sea.
The US Navy said it had notified Moscow of the upcoming operation on Friday "to avoid misperceptions, reduce risk, and prevent inadvertent escalation."
US officials have consistently said that Russia has boosted its military presence in the Arctic in recent years.
"Russia has gradually strengthened its presence by creating new Arctic units, refurbishing old airfields and infrastructure in the Arctic, and establishing new military bases along its Arctic coastline,"
a Pentagon report on the Arctic said last year.
"There is also a concerted effort to establish a network of air defense and coastal missile systems, early warning radars, rescue centers, and a variety of sensors," the report added.
Late last month NATO jets intercepted Russian military aircraft in the area on two occasions.
Last Tuesday "a Russian Airborne Early Warning aircraft as well as two Russian Tu-22 long range bombers with fighter escorts approached NATO airspace off the coast of Norway and were intercepted by Norwegian fighter jets," NATO said in a statement late last month.
The following day Norwegian F-16 and F-35 fighters once again intercepted Russian aircraft, this time two maritime patrol planes, after they approached "NATO airspace close to Norway," according to NATO.
The UK's Royal Air Force also launched Typhoon fighter aircraft to meet and escort the Russian planes as they tracked south toward the North Sea.
The US and Russian militaries often find themselves operating in close proximity in and around Europe.
Last month the
US military accused Russian jets of twice endangering the crew of a US Navy surveillance plane flying in international airspace in the eastern Mediterranean after the Russian aircraft performed what the Navy called "unsafe and unprofessional" intercepts.
