A large Bomber Task Force reportedly consisting of up to six B-52 Stratofortress heavy long-range bombers are flying into Europe this week.

The rotation, which comes at a time of heightened tension with Russia, is focused on interoperability training, but there is a deterrent element as well.

This week, B-52 bombers also flew over the disputed South China Sea, where the US and China have repeatedly found themselves at odds.

US Air Force B-52 Stratofortress heavy long-range bombers are flying into Europe this week, US Air Forces Europe - Africa announced Thursday, at a time Russia is leveling threats against the US as a Cold War-era missiles ban collapses.

A Bomber Task Force consisting of bombers from the 2nd Bomb Wing out of Barksdale Air Force Base in Louisiana are deploying to the US European Command area of operations.

While USAFE, citing operational security concerns, would not provide the number of bombers heading into this theater, Military.com reports that up to six B-52 bombers will arrive in the United Kingdom before the weekend. An unnamed source told the outlet that this marks the largest deployment of a bomber platform to the Europe since 2003, when EUCOM had 20 bombers at Royal Air Force Fairford station during Operation Iraqi Freedom.

The deployment is focused on interoperability training with the British Royal Air Force, as well as other allies and partners in the region. At the same time, there is also a deterrence element to this deployment, USAFE told Business Insider.

A U.S. Air Force B-52 Stratofortress pulls away from a KC-135 Stratotanker from the 100th Air Refueling Wing, RAF Mildenhall, England, after receiving fuel off the English coast, March 14, 2019. U.S. Air Force photo by Tech. Sgt. Emerson Nuñez

'Training with joint partners, allied nations and other U.S. Air Force units contributes to our ready and postured forces and enables us to build enduring and strategic relationships necessary to confront a broad range of global challenges," USAFE said in a statement.

The US has routinely rotated bombers into Europe as part of Operation Atlantic Resolve, an apparent response to Russia's annexation of the Crimea in 2014. That year, the US reportedly sent two B-2 Spirit bombers and three B-52s to Europe, planes that are capable of carrying nuclear weapons.

The current deployment comes at a time of increased tension between Washington and Moscow. The collapse of a Cold War-era arms control agreement — the Intermediate-Range Nuclear Forces Treaty — has ignited an arms race and led to threatening rhetoric from Russia.

Read More: In threatening state of the nation address, Putin threatens to target the US with new weapons if it puts missiles in Europe

A U.S. Air Force B-52 Stratofortress approaches a KC-135 Stratotanker from the 100th Air Refueling Wing, RAF Mildenhall, England, before receiving fuel above the English coast, March 14, 2019. U.S. Air Force photo by Tech. Sgt. Emerson Nuñez

This week, US Global Strike Command kicked off Global Lightning 2019, a battle staff exercise designed to assess joint operational readiness across all of USSTRATCOM’s mission areas, which happens to be EUCOM this year. This exercise will reportedly also include a B-52 mission.

US Air Force B-52s are bombers with the ability to carry both conventional and nuclear weapons payloads. As America's longest-serving bomber, these aircraft have been flying for over six decades. They are expected to continue flying as the service continues to upgrade these aircraft to not only keep them in the fight, but make them deadlier than ever before.

Read More: US B-52 bombers are getting an upgrade that will let them drop smart bombs like never before

B-52s have also been active in the Pacific theater this month, flying through the contested South China Sea twice in ten days. These routine flights typically aggravate China, as they're intended to show the US doesn't recognize China's expansive claims; China has called the flights "provocative."

"U.S. aircraft regularly operate in the South China Sea in support of allies, partners, and a free and open Indo-Pacific. U.S. Pacific Air Forces bombers have flown from Guam for more than a decade as part of U.S. Indo-Pacific Command’s Continuous Bomber Presence operations," Pacific Air Forces told Business Insider in a statement.

Read More: The US sent a B-52 bomber through the South China Sea for the first time in months