Story highlights The two U.S. Air Force aircraft are on a training mission

Aim is to become familiar with air bases and operations in the area, Air Force says

For local residents, the stealth bombers are a sight

Two of the United States' most recognizable military aircraft -- a pair of B-2 stealth bombers -- caught the eyes of residents as they arrived in Europe this week for training.

"They seem to defy science!" said one Twitter user in Cirencester, England, who saw one of the stealth bombers in flight.

The bombers' unique radar-evading design always draws attention, as does this training mission in particular, which comes at a time of conflict in Ukraine.

An Air Force news release about the mission did not mention the Ukraine crisis, but U.S. fighter jets have previously been deployed to Europe on similar training missions to show support for NATO allies.

Photos: Photos: B-2 stealth bomber Photos: Photos: B-2 stealth bomber B-2 stealth bomber – The U.S. Air Force deployed two B-2 stealth bombers to Europe in 2014 to conduct training flights and become familiar with air bases and operations there. Click through the gallery to learn more about the aircraft. Hide Caption 1 of 7 Photos: Photos: B-2 stealth bomber B-2 stealth bomber – Maintainers and crew chiefs prepare a B-2 at Whiteman Air Force Base in Missouri in March 2011. There are only 20 B-2s in the Air Force fleet. All are based at Whiteman in the 509th Bomb Wing. Hide Caption 2 of 7 Photos: Photos: B-2 stealth bomber B-2 stealth bomber – A B-2 takes flight from Whiteman in April 2011. The B-2 is operated by a crew of two -- a pilot in the cockpit's left seat and a mission commander in the right. Hide Caption 3 of 7 Photos: Photos: B-2 stealth bomber B-2 stealth bomber – A KC-135 Stratotanker refuels a B-2 during a training mission in August 2012. The B-2 is powered by four General Electric F118-GE-100 engines, and it can travel 6,000 miles without refueling. Hide Caption 4 of 7 Photos: Photos: B-2 stealth bomber B-2 stealth bomber – A B-2 takes off from Whiteman for a training run to Alaska in October 2002. B-2s can carry conventional or nuclear weapons. The planes have flown combat missions over Iraq, Afghanistan and Kosovo. Hide Caption 5 of 7 Photos: Photos: B-2 stealth bomber B-2 stealth bomber – A B-2, left, flies near Osan Air Base in Pyeongtaek, South Korea, in March 2013. The B-2 has a wingspan of 172 feet, a length of 69 feet and a height of 17 feet. Hide Caption 6 of 7 Photos: Photos: B-2 stealth bomber B-2 stealth bomber – Airman 1st Class Steven McCray, a B-2 crew chief, performs pre-flight checks at Whiteman in April 2013. Each B-2 costs about $1.16 billion. Hide Caption 7 of 7

JUST WATCHED Secret new stealth drone exposed Replay More Videos ... MUST WATCH Secret new stealth drone exposed 02:06

The mission for the pair of stealth bombers, the Air Force said, is to conduct flights in Europe and to become familiar with air bases and operations in the area.

"This deployment of strategic bombers provides an invaluable opportunity to strengthen and improve interoperability with our allies and partners," said Adm. Cecil Haney, commander of U.S. Strategic Command. "The training and integration of strategic forces demonstrates to our nation's leaders and our allies that we have the right mix of aircraft and expertise to respond to a variety of potential threats and situations."

The B-2s are assigned to the 509th Bomb Wing at Whiteman Air Force Base in Missouri.

"Just saw a Stealth Bomber fly over our house," another resident said on Twitter. "Amazing aircraft. My son wanted to know if Batman was flying it."