US B-52 bombers arrived in the European theater of operations in mid-March to train with allies and partners.

A U.S. B-52 Stratofortresses, deployed from Barksdale Air Force Base, La., flies in formation with three Norwegian F-16 Fighting Falcons over Norway, March 28, 2019.
A US B-52 Stratofortresses, deployed from Barksdale Air Force Base, Louisiana, in formation with three Norwegian F-16 Fighting Falcons over Norway, March 28, 2019.
US Air Force

Read More: A big batch of B-52 bombers is flying into Europe amid heightened tensions with Russia

With a half-dozen B-52s in Europe, the US military currently has more of these bombers operating there than it has at any time since 2003. Noticeably on edge, Russia has been highly critical of the ongoing training exercises.

Three B-52 Stratofortresses deployed from Barksdale Air Force Base, La., fly a sortie in support of U.S. Strategic Command’s Bomber Task Force in Europe over Norway, March 28, 2019.
Three B-52 Stratofortresses fly a sortie over Norway in support of US Strategic Command’s Bomber Task Force in Europe, March 28, 2019.
U.S. Air Force photo by Airman 1st Class Tessa B. Corrick

While the US military insists the flights demonstrate US "commitment to allies and partners through the global employment of military forces," the Kremlin has argued that US and NATO actions are detrimental to regional security and stability.

Source: Military.com, Fox News

On March 28, five US B-52s operating out of RAF Fairford drilled alongside Norwegian F-16s in the vicinity of the Norwegian Sea.

Five B-52 Stratofortresses, deployed from Barksdale Air Force Base, La., fly in formation with three Norwegian F-16 Fighting Falcons over Norway, March 28, 2019.
Five B-52 Stratofortresses in formation with three Norwegian F-16 Fighting Falcons over Norway, March 28, 2019.
U.S. Air Force photo by Airman 1st Class Tessa B. Corrick

Some of the recent training flights involving the B-52s have reportedly included mock strikes on surface targets.

Source: US Air Forces in Europe, The War Zone

On the same day, two Russian Tu-160 Blackjack bombers, accompanied by MiG-31 interceptor aircraft, conducted drills over the Norwegian Sea, the Russian Defense Ministry said.

Tupolev Tu 160 strategic bomber
A supersonic Tu-160 strategic bomber.
Alexei Panov, Sputnik, Kremlin Pool Photo via AP

While US bombers have been flying training in northern Europe, Russian Tu-160 and Tu-95 bombers have been conducting exercises nearby by way of the Barents Sea.

A Norwegian military spokesperson told The Barents Observer that Russian bomber flybys are "neither sensational nor abnormal." She said that Norwegian fighters were scrambled to identify the bombers when they passed by on March 28.

Sources: The Barents Observer, TASS, Sputnik

Russia has repeatedly scrambled fighters to intercept B-52 bombers training in Europe, and NATO countries have, in turn, sent aircraft to intercept Russian bombers.

A B-52 Stratofortress deployed from Barksdale Air Force Base, La., flies a sortie in support of U.S. Strategic Command’s Bomber Task Force in Europe over Norway, March 28, 2019.
A B-52 Stratofortress flies a sortie over Norway in support of US Strategic Command’s Bomber Task Force in Europe, March 28, 2019.
U.S. Air Force photo by Airman 1st Class Tessa B. Corrick

British Royal air force aircraft intercepted the Russian Tu-160 Blackjack bombers over the North Sea, the British Defense Ministry said in a statement.

US Air Forces in Europe told Business Insider that interactions with Russian aircraft have been largely professional.

This is not the first time the US and Russian militaries have found themselves in close proximity in recent months. A similar situation occurred during NATO's Trident Juncture exercise late last year.

Capt. Richard “Hash” Brown, 20th Bomb Squadron B-52 Stratofortress pilot deployed from Barksdale Air Force Base, La., looks out the window during a flight over Norway, March 28, 2019. B-52s are capable of flying at high subsonic speeds at altitudes up to 50,000 feet.
Capt. Richard "Hash" Brown, a 20th Bomb Squadron B-52 Stratofortress pilot, during a flight over Norway, March 28, 2019.
U.S. Air Force photo by Airman 1st Class Tessa B. Corrick

As US and NATO troops trained together in Norway in late October and early November during the alliance's largest exercise in years, Russia decided to hold missile drills in the Norwegian Sea, not far from NATO forces.

Five B-52 Stratofortresses deployed from Barksdale Air Force Base, La., fly a sortie over Norway, March 28, 2019.
Five B-52 Stratofortresses fly a sortie over Norway, March 28, 2019.
U.S. Air Force photo by Airman 1st Class Tessa B. Corrick

Russia also sent a Tu-142 long-range reconnaissance aircraft to spy on the exercises in early November.

Read More: Russia aims its missile drills shoulder-to-shoulder with NATO's biggest war games in years

It is unclear how long the US B-52 bombers will be in Europe.

Four B-52 Stratofortresses deployed from Barksdale Air Force Base, La., fly a sortie in support of U.S. Strategic Command’s Bomber Task Force in Europe over Norway, March 28, 2019.
Four B-52 Stratofortresses fly a sortie over Norway in support of US Strategic Command’s Bomber Task Force in Europe, March 28, 2019.
U.S. Air Force photo by Airman 1st Class Tessa B. Corrick

Frequent encounters between Russian and US aircraft in the region, which have sometimes been dangerously close, have been characterized as a return to Cold War behavior, raising concerns that such interactions could led to accidents or fatalities and potentially escalate.