Washington: The US Air Force has flown two F-22 Raptor fighter jets to Romania to deter further Russian intervention in Ukraine.
The jets landed at Mihail Kogalniceanu air base, close to the Black Sea port of Constanta in southeast Romania, on Monday.
A US statement said the aircraft possess sophisticated sensors which would allow pilots to track, identify, shoot and kill air-to-air threats without being detected.
They can also attack surface targets.
Russian-backed separatists have been fighting government troops in Ukraine since April 2014, with at least 9,100 people killed.
The conflict has left neighbouring countries in eastern Europe concerned over future Russian aggression in the region.
US Ambassador Hans G Klemm said the US and Romania – which has been a NATO member since 2004 – were seeking to improve “the defence of Europe, the defence of the North Atlantic Alliance, to improve the security in south eastern Europe… as a result of the aggression by Russia that has brought so much instability to this part of the world over the past two to three years”.
Major General Laurian Anastasof, Romania Air Force chief, has voiced concerns about Russia’s intentions in the region.
He said that if an unidentified aircraft comes within 20 miles of Romanian airspace, NATO’s procedure “obliges us to scramble planes up in the air, a scenario that has already happened four times this year”.
The F-22 Raptors, which arrived from the UK, are part of the Operation Atlantic Resolve, a US commitment to NATO’s collective security and regional stability.
In 2014, President Obama promised to bolster defences of NATO’s members in eastern Europe following Russia’s annexation of the Crimean peninsula.
The US has deployed 12 F-22s at an air base in Lakenheath, eastern England. US Congress has banned makers Lockheed Martin from selling them abroad because they are almost impossible to detect on radar.
The two sent to Romania were expected to fly back to the UK on Monday night.
It comes after two Russian aircraft flew simulated attack passes near a US guided missile destroyer in the Baltic Sea earlier this month.