U.S., Canadian, German, French, United Kingdom, Romanian and Ukrainian observers were aboard the flight.
'The timing of this flight is meant to reaffirm US commitment to Ukraine and other partner nations, ' the Pentagon said.
The Boeing OC-135 aircraft flew near Russian Federation in an operation permissible under the Treaty on Open Skies, a programme of unarmed surveillance flights involving 34 countries.
The Open Skies Treaty permits each of the 34 state parties the right to gather information about the military forces and activities of other state parties, but an extraordinary flight allows countries to conduct the flights on a bilateral basis.
The "challenge" was shrugged off and mocked by the Kremlin, who said on Thursday the vessel hadn't come closer than 62 rules to Russian territorial waters, adding it got "away at maximum speed" as Moscow's ships followed it.
Typically all 34 parties to Open Skies, including Russian Federation, would have to approve a reconnaissance mission as part of a package of flights.
Ukrainian Defense Minister Stepan Poltorak told reporters on Friday that his country intends to send naval ships through the Kerch Strait soon, saying that "otherwise Russian Federation will fully occupy the Sea of Azov".
An OC-135B Open Skies aircraft takes flight on August 13, 2015, at Offutt AFB, Neb.
The flight comes on the heels of an unusual U.S. Navy freedom-of-navigation operation in the vicinity of Peter the Great Bay.
A U.S. guided-missile destroyer was deployed to disputed waters off the Russian coast on Wednesday in a rare show of force not seen since the Cold War. "Our U.S. 6th Fleet is always prepared to respond where called", Cmdr.
Two Ukrainian armoured gunboats, the Lubna and the Kremenchug, escorted a vessel carrying a Bulgarian flag from the Ukrainian port of Mariupol through the Kerch Strait, Vice Admiral Aleksei Volsky, first deputy head of Russia's FSB coast guards, told a briefing in Moscow on Saturday.
The United States has begun making preparations to sail a warship into the Black Sea amid Russia-Ukraine tensions, CNN has reported.