Russia kicks against U.S plans to send the F-22 to Europe as part of its commitment to its Allias.

The U.S. Air Force could be sending some of its most advanced warplanes to Europe in a show of force against Russian actions in Ukraine and elsewhere around the continent, the service's top civilian said Monday.

"The biggest threat on my mind is what's happening with Russia and the activities of Russia," Secretary of the Air Force Deborah James said during a visit to the Paris Air Show. "It's extremely worrisome on what's going on in the Ukraine."

James' remarks were reported by Military.com, Breaking Defense and other websites.

For months, the Pentagon has been rotating aircraft through Europe for exercises with allies under Operation Atlantic Resolve, which it calls "America's commitment to European security."

Participating in those exercises and rotations have been B-2 and B-52 bombers, F-15Cs and A-10 attack planes as well as Army and Navy assets.

James said the F-22 Raptor, the Pentagon's premier fighter, could join that list.

"I could easily see the day -- though I couldn't tell you the day exactly -- when the F-22, for example, rotates in is a possibility. I don't see why that couldn't happen in the future," James said, according to Military.com.

The stealthy F-22s, which became operational in 2005 but only saw their first combat in attacks on ISIS positions in Syria late last year, can be configured to attack other aircraft or bomb ground targets.

"The F-22 cannot be matched by any known or projected fighter aircraft," says the Air Force's fact sheet for the Raptor, which costs about $143 million each. That would include what Russia currently puts in the air. Russian reaction to James' remarks came through state-sponsored media Sputnik International.

One posting on the Sputnik website called any threat from Russia "fictional." Another said Moscow would make moves of its own if the F-22s were deployed.

"Their deployment will certainly be an additional impetus for Moscow to speed up the process of developing and putting on service the Russian response, the fifth-generation T-50 fighter," Sputnik quoted Vladimir Batyuk, from the Institute for U.S. and Canadian Studies of the Russian Academy of Sciences, as saying.

U.S. and Russian forces have had several close calls around Europe since Russian forces took Crimea from the Ukraine in 2014 and supported rebels in other areas of the former Soviet bloc state.

Late last month, a Russian fighter jet, flying at high speed, came within 10 feet of a U.S. Air Force reconnaissance aircraft in international airspace over the Black Sea, U.S Official said

That close call came weeks after another incident between the U.S. and Russia over the skies of Europe, when a U.S. RC-135U flying a routine route in international airspace was intercepted by a Russian Su-27 Flanker in what authorities called an "unsafe and unprofessional manner."

And earlier this month, the U.S. Navy took the unusual step of releasing video of Russian Su-24 aircraft flying past the right side of the guided missile destroyer USS Ross in the Black Sea.