A NATO E-3A AWACS plane will fly over Romanian airspace as part of a planned exercise on Tuesday, Romania's defense ministry said, Reuters reported.
NATO had said AWACS (airborne early warning and control) planes will fly from their home airbases in Geilenkirchen, Germany, and Waddington in Britain.
The Romanian ministry said AWACS planes fly at an altitude of 9,000 meters (5.6 miles), their radar can survey an area of up to 312,000 square kilometers and can detect low-flying targets.
The NATO alliance said on Monday it will start reconnaissance flights over Poland and Romania to monitor the situation in neighboring Ukraine where Russian forces have taken control of Crimea.
Ukraine is not a NATO member but Russia's intervention in Crimea has alarmed neighboring countries, including alliance members that used to be dominated by the Soviet Union.
As a result of protests in Ukraine, the country's President Viktor Yanukovych was ousted on Feb. 22. The Verkhovna Rada (parliament) has approved the new composition of the parliament and is preparing to hold pre-term elections.
On Feb. 26 several thousand people participating in two rallies gathered in front of Supreme Council of Crimea. After the escalation of the protest actions in Crimea, the Federation Council supported President Vladimir Putin's appeal regarding the use of the Russian Armed Forces in Ukraine pending "the normalization of the socio-political situation in that country".
Leaders of Canada, France, Germany, Italy, Japan, UK and the U.S., as well as chairman of the European Council and the chairman of the European Commission made a joint statement condemning Russia's position on Ukraine and canceled the preparations for the G8 summit in Sochi, scheduled for June 2014.