The Western military alliance has strengthened its presence in the region since Russia invaded Ukraine, which borders Romania, a NATO member.

"Our AWACS (Airborne Warning and Control System planes) can detect aircraft hundreds of kilometres away, making them a key capability for NATO's deterrence and defence posture," NATO spokesperson Oana Lungescu said in a statement.

The planes will arrive on Tuesday in Otopeni, near Bucharest, and are part of a fleet of 14 NATO Boeing E-3A AWACS aircraft, usually based in Geilenkirchen, western Germany.

NATO did not say how many of its AWACS aircraft would be deployed to the patrols from Romania.

Each AWACS plane can typically stay in the air for eight and a half hours at an altitude of 9,000 metres (30,000 feet). While airborne, they can monitor an area almost as big as Poland and can extend their flight time with air-to-air refuelling.

Around 180 military personnel will be based at a Romanian air base in Otopeni to provide aircraft support. The mission will last several weeks, NATO said.

Since Russia invaded Ukraine last February, NATO has reinforced its air presence in eastern Europe with additional fighter jets, surveillance aircraft and air tankers.

The alliance has also launched regular patrols over eastern Europe and the Baltic Sea region to track Russian jets near NATO countries' borders.

One of NATO's eight multinational battlegroups in eastern Europe is deployed in Romania in a deterrence-and-defence posture.

csg-raz/rmb/fb

BOEING