A US plane flew over Russian airspace, taking photos of military equipment, as a part of a surveillance mission conducted by the American army, a report said on Wednesday.

A US plane flew over Russian airspace, taking photos of military equipment, as a part of a surveillance mission conducted by the American army, a report said on Wednesday.

American newspaper, Stars and Stripes reported that a US observation plane has been flying over Russian skies during the past several days.

The mission was done under the Open Skies Treaty that allows a limited number of observation flights, the report added. Russia, the United States and a number of other countries have signed the treaty.

“Most of the world has no idea this treaty even exists,”  the US daily quoted Navy Commander Chris Nelson, who is overseeing the mission this week, as saying.

“Whenever I mention that Russians fly aircraft over the US taking pictures, it blows people’s minds,” he added.

The surveillance mission comes amid escalating tensions between Washington and Moscow over the Ukraine crisis.

President Barack Obama accuses Russian President Vladimir Putin of supporting pro-Russian separatists in eastern Ukraine. The Kremlin, however, denies the accusation.

The Obama administration and the European Union have so far imposed sanctions on Moscow over the issue.