An incredible photo taken Saturday showed a Russian surveillance plane flying over Boston.
>> Read more trending news
A photographer with The Boston Herald took the photo in South Boston and estimated the plane to be only about 3,600 feet high -- less than a mile above the ground and one-tenth as high as cruising altitude for most commercial flights.
The flight was sanctioned because of what is called the Open Skies Treaty, an international program that allows unarmed aerial surveillance flights over participating nations, Boston25News.com reported.
Russia and the United States are two of the 34 nations in the agreement.
The same Russian plane was spotted over Washington D.C. last week. It has been conducting missions based out of an Air force base in Ohio.