Here's What You Need to Remember: As recently as late 2019, NATO was the one launching patrol planes to keep watch over Russian submarines.

A pair of Russian navy Tu-142 patrol planes flew one of the longest-ever flights in international air space in decades on and around March 11, 2020.

The powerful, swept-wing planes with their four turboprop engines flew from Kipelovo-Fedotovo airbase near Vologda in northern Russia, skirted the Arctic Circle as they headed west around Norway and the United Kingdom then south to the waters off Spain -- and then flew back.

NATO fighters rose to intercept the 174-feet-long Tupolevs, but at no point did the planes, which are based on the Tu-95 bomber, stray into any country’s national air space.

The impressive flight was just the latest in a surge of sorties by the small fleet of around two dozen Tu-142s, which with their nearly 8,000-mile endurance are among the farther-flyest military aircraft in the world.

The Tu-142 and other Russian long-range warplanes have flown several epic missions in the spring of 2020, in part in order to keep tabs on NATO submarines conducting exercises in European and Arctic waters.

The Russian sorties mirror a similar surge by NATO patrol planes that took place in late 2019 as the Russian fleet deployed an unusually large number of submarines. The escalating missions below and above the waves point to intensifying preparation for a potential war on both sides of the former Iron Curtain.

The March 11, 2020 sortie might have targeted NATO submarines participating in the alliance’s Cold Response war game. NATO canceled Cold Response in reaction to the rapid spread of the flu-like novel-coronavirus, but the submarines may have lingered in the exercise zone.

The Norwegian air force scrambled fighters to check in on the Tu-142s as they passed by Norway. It’s unclear which types the Norwegians launched, but Oslo’s air arm earlier in March 2020 sent F-16 and F-35 fighters to intercept a patrol by a Tu-142 and an escorting MiG-31 interceptor.

The Royal Air Force with its Typhoon fighters took over as the Russian patrol planes neared United Kingdom air space. “These Russian bombers do not comply with international air traffic rules, are a hazard to airliners and are not welcome in our air space,” Air Chief Marshal Mike Wigston stated. “RAF Typhoons, alongside our NATO allies, ensured these Russian aircraft posed no hazard.”

But the Russians were back at it a few days later with a pair of Tu-160 long-range bombers. Again, RAF fighters rose to intercept.

British and Norwegian Typhoon and F-16 fighter jets also scrambled twice in late February 2020 to intercept pairs of Tu-142s after the Russian planes flew farther south than normal and approached Norwegian air space.

The Russian patrol surge isn’t limited to Europe. On March 9, 2020, a pair of Tu-142s took off from Russia’s Far East region and flew northeast over the Arctic.

U.S. Air Force F-22s and Canadian air force F/A-18s simultaneously intercepted the patrollers and followed them as they flew over a temporary base for two U.S. Navy submarines conducting the service’s biennial ice exercise.

American sailors captured dramatic images of the Russian planes buzzing USS Connecticut and USS Toledo.

“The Arctic is a potential strategic corridor -- between Indo-Pacific, Europe and the U.S. homeland -- for expanded competition," U.S. Navy vice admiral Daryl Caudle explained in a statement.

As recently as late 2019, NATO was the one launching patrol planes to keep watch over Russian submarines. The Russian navy in mid-October 2019 deployed eight submarines in the country’s biggest undersea exercise since the Cold War.

More than a dozen NATO patrol planes flew back-to-back missions in order to find and track Moscow’s submarines.

Between Oct. 25 and Nov. 7, 2019, the NATO planes flew more than 40 missions. Six Norwegian air force P-3s, four U.S. Navy P-8s and a Canadian air force CP-140 flew from Andoya in Norway. At least one additional P-8 flew from Keflavik in Iceland. A French navy Atlantic 2 patroller staged from Prestwick airport in Scotland.

The Russian exercise seemed to highlight Moscow’s new approach to undersea warfare. While the war game reportedly was defensive in nature, the same submarines with their long-range cruise missiles could conduct offensive operations from the same waters.

David Axe served as Defense Editor of the National Interest. He is the author of the graphic novels War Fix, War Is Boring and Machete Squad. This article first appeared last year.

Image: Reuters.