A U.S. Air Force RC-135 Rivet Joint spy plane reportedly violated Swedish air space in order to dodge Russian fighter jets, according to a Swedish media outlet.

According to DN.se, on July 18 the RC-135—a four-engine Boeing with sensitive receivers for detecting radar signals and other electronic emissions—was flying a surveillance mission over the Baltic Sea near Russia when Russian jets rose to meet it … and the American plane turned and fled across Sweden.

U.S. European Command confirmed the violation on Aug. 2 but insisted it was an accident. “The U.S. aircraft was directed towards Swedish air space incorrectly by U.S. personnel,” the command said in a statement.

American signals-intelligence aircraft from Mildenhall air base in the U.K. regularly have been flying sorties in international air space over the Baltic ever since Russia invaded Ukraine in February. The SIGINT planes help Washington monitor Russian troops’ movements.

On July 18, the Russians twice sent fighters from Kaliningrad to intercept the RC-135.

Close encounters between rival warplanes are a frequent occurrence, with Russian and American planes intercepting each other all around the world. It’s standard practice for intercepting fighters to fly close to snooping spy planes—in essence, watching the watchers.

But the RC-135 reacted oddly to the Russian jets’ second intercept attempt. The Rivet Joint crew asked Swedish authorities for permission to cross into Swedish air space. When air traffic control denied the request, the RC-135 flew over Sweden’s Gotland Island anyway.

After overflying Sweden’s largest island, the Rivet Joint turned south into international air space before reportedly re-entering Swedish air space near Oland.

The Rivet Joint “vectored out of the [Swedish] air space once the Swedish air traffic controllers informed them of the error,” according to European Command.

U.K.-based RC-135s have flown more than 50 missions in the region since February, sometimes flying over Poland, Lithuania or Latvia and sometimes over the Baltic Sea near Kaliningrad. But according to DN.se, this was the first time that an American plane has reacted to an interception attempt by taking an unauthorized short-cut over Sweden.

Violations of Swedish air space occur quite frequently—and sometimes the Swedes send Gripen jets to intercept. There have been at least seven violations in 2014 … and 53 in all since 2009, DN.se reported.

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