NATO plans to monitor Russia's border with member nations Poland and Romania amid the crisis in Ukraine, according to a report.
The 28-member alliance gave the green light to deploy reconnaissance planes on Monday, a spokesman told the BBC.
"All Awacs [Airborne Warning and Control System] reconnaissance flights will take place solely over alliance territory," the official said.
The move came after Russia invaded Ukraine's Crimea region, where officials are holding a referendum Sunday on whether to join Russia. Ukraine and the West say this is illegal.
NATO said the surveillance flights would "enhance the alliance's situational awareness."
Last week, the intergovernmental military alliance said it was reviewing all cooperation with Russia while engaging with the new government formed in Kiev after President Viktor Yanukovych was ousted.