Canadian fighter jets have intercepted Russian bombers off Canada’s northern coast for the first time in more than two years, as relations between Moscow and the West continue to worsen.

Two CF-18s were scrambled on Thursday after North American early-warning air defences spotted two TU-95 Bear bombers approaching Alaskan and Canadian airspace from the west around 7 p.m.

The long-range bombers, which can carry nuclear weapons, were also tracked by U.S. F-22 jets based out of Alaska, said North American Aerospace Defence Command spokeswoman Maj. Jennifer Stadnyk.

Stadnyk said the Russians never entered Canadian or American airspace, and acted “professionally and safely” before returning to their home base.

The incident marked the first time since December 2014 that Canadian fighter jets have been scrambled to intercept Russian military aircraft flying in the Far North.

It was also the fourth time in as many days that Russian aircraft have been spotted approaching North American airspace. Norad also dispatched F-22s on Monday to track Bear bombers that were flying near Alaska.

Two TU-95s were also spotted near Alaskan airspace on Tuesday while two IL-38 maritime patrol aircraft were tracked on Wednesday, though Norad opted not to scramble fighters in either case.

“We haven’t seen this level of activity since July 2015,” Stadnyk said, though she added: “It’s not unprecedented. What they’re doing this week is very similar to what they used to do.”

Such Russian bomber flights over the Far North were a regular occurrence between 2012-14, Stadnyk said, before the TU-95s were grounded over safety concerns.

One of the bombers skidded off a runway on June 8, 2015, and caught fire, killing a crew member and injuring several more.

The resumption of Russian flights over the Arctic this week comes at a key moment for Russia and the West, whose relationship has reached what U.S. Secretary of State Rex Tillerson recently called “a low point.”

Ties between Moscow and Washington have been particularly strained ever since the U.S. launched a cruise-missile strike against Syria, which it blamed for a chemical attack that killed more than 80 people earlier this month.

Relations between Ottawa and Moscow have not been spared, despite the Liberal government’s initial plan to re-engage Russia.

Prime Minister Justin Trudeau called out the Kremlin earlier this month for supporting the Syrian government of president Bashar Assad, who is widely seen by the West as being responsible for the attack.

More than 450 Canadian troops are also preparing to head to Latvia in the next few weeks, where they will lead a NATO force intended to check Russian aggression in eastern Europe.

And Foreign Affairs Minister Chrystia Freeland remains on a list of individuals banned from visiting Russia, after Canada slapped the country with sanctions for annexing Crimea in 2014.

Steve Saideman, a political science professor at Carleton University’s Norman Paterson School of International Affairs, said the Russians could be trying to send a signal to the Trump administration.

But he noted the Russians have been conducting such military flights throughout Europe and Asia for years, “so if it’s a message to Trump, what’s the message?”