A U.S. reconnaissance plane crossed into Swedish airspace last month as it sought to avoid being intercepted by Russian fighters, a news report said, citing U.S. military officials.
The episode occurred on July 18 when Russian aircraft approached an Air Force RC-135 electronic surveillance plane as it was flying in what U.S. officials said was international airspace over the Baltic Sea, the New York Times said.
"The aircraft commander, acting in a professional and safe manner, maneuvered the aircraft to avoid a possible encounter by Russian aircraft," the United States European Command said in a statement, according to the Times.
Ties between the U.S. and Russia have plunged to their lowest level since the end of the Cold War over the crisis in Ukraine, which Washington accuses Moscow of fanning with weapons and support for rebels fighting the Kiev government.
The U.S. has expanded its intelligence-gathering in the region, including reconnaissance missions by RC-135 aircraft, the Times said.
It said that according to Swedish news media, the episode last month occurred as the RC-135 aircraft was flying near Kaliningrad, a heavily militarized Russian enclave between Poland and Lithuania that includes a major port for the Russian Baltic fleet.
After being approached by Russian aircraft, the RC-135 pilot sought to avoid the encounter by maneuvering his aircraft into Swedish airspace, flying over Gotland Island.
Sweden is not a member of NATO, and the European Command said in its statement that the RC-135 had been directed toward Swedish territory "incorrectly by U.S. personnel," the Times reported.
The plane left Swedish airspace after Swedish air traffic controllers informed the aircraft of the mistake, the newspaper said.