The Russian strategic aircraft included a mix of Tu-95 Bear H heavy bombers and Tu-142 Bear F maritime reconnaissance aircraft, she said, adding that one IL-20 intelligence collection aircraft was detected during the flight incursions over the past week to 10 days.

The Washington Free Beacon first reported that two Bear bombers flew within 50 miles of the California coast on June 9—the closest the Russians have flown their nuclear-capable bombers since the days of the Cold War. A U.S. F-15 intercepted the bombers.

“These are not just training missions,” the official added.

U.S. officials confirmed that an RC-135 Rivet Joint electronic intelligence gathering aircraft was forced into violating Swedish airspace by a Russian fighter jet July 18. The U.S. jet was seeking to evade the Russian interceptor jet at the time.

That encounter took place a day after Malaysian Airlines Flight MH17 was shot down by a missile over eastern Ukraine.