A secret Cold War-era deal lets British jets shadow Russian bombers when they fly near a vital Atlantic chokepoint

• Since the 1950s, Ireland has allowed British jets to intercept Russian aircraft near Irish airspace.
• Ireland's west coast overlooks North Atlantic waters that the Russians and NATO keep a close eye on.
• The deal allowing the intercepts has long been secret, and Irish lawmakers now want more details.

If Russian bombers fly near Ireland, they may be intercepted by fighter jets — but not Irish ones.

Under a secret agreement between the UK and the Republic of Ireland that dates back more than 70 years, Britain will defend Irish airspace from intrusions by Russian aircraft and other aerial threats.

The deal has been amended by Irish leaders over the years, but it has also been kept secret due to Irish memories of British rule and tensions over Northern Ireland, which remained a part of the UK after Ireland was partitioned in 1921.

The deal now faces rising backlash, however. An Irish senator filed a lawsuit last year arguing the deal is unconstitutional. The growing power of Sinn Fein — an Irish republican party historically opposed to British influence — could also affect the future of the agreement.

On the other hand, rising tensions between the West and Russia could jeopardize Ireland's traditional neutrality and challenge its meager military, which is primarily oriented for UN peacekeeping missions.

There is "growing alarm among the Irish public and its European governmental neighbors at Ireland's woefully neglected defense capabilities," Michael Mulqueen, a professor at Britain's University of Central Lancashire and an expert on Irish national security, told Insider.

With barely any warplanes and few anti-aircraft weapons, Ireland has little ability to defend its airspace, whether from Russian bombers, hijacked airliners, or even drug smugglers in private jets. According to the Irish Times, Ireland is probably more dependent on Britain for air defense now "than at any point since the first agreement in 1952."

Since 2014, when Russia seized Crimea and set off a new period of tensions, British fighters have scrambled several times to intercept Russian bombers off Ireland's west coast. Russia also conducted live-fire naval exercises off the Irish coast in 2022, despite Irish protests.

Ireland has also been lumped in to the Kremlin's threats to the UK: In 2022, Moscow threatened to annihilate the British Isles with a nuclear-induced tsunami, releasing an animated video that showed the bomb detonating off the coast of Northern Ireland.

The ire over the deal reflects Britain and Ireland's contentious relationship. There are bitter memories on both sides but also a long history of exchange. Despite Ireland's neutrality in World War II, an estimated 80,000 of its citizens joined the British military, and its government allowed British anti-submarine aircraft to fly over Irish territory to hunt German U-boats.

The current Anglo-Irish defense agreement is rooted in mutual practicality. Ireland occupies a strategic position on the UK's western flank and adjacent to the Greenland-Iceland-UK Gap, a vital maritime chokepoint that the British and other NATO militaries are keen to monitor.

During the Cold War, British aerial protection spared a small nation — and a poor one in the 1950s — the need to fund expensive air defenses. Beefing those defenses up now would essentially mean starting from scratch.

The Irish military has a few short-range RBS-70 surface-to-air missiles that can reach 16,000 feet, backed by Giraffe search radars. When President Joe Biden visited Ireland in April, there were fears he would be vulnerable because the Giraffes weren't working.

In 1998, the Irish Air Corps replaced its only jets — a handful of old French-made Fouga Magister trainers — with eight PC-9M Pilatus propeller-driven trainers that have "speed, height, and agility capabilities broadly equivalent with that of British Hurricanes and Spitfires of World War II," Mulqueen said.

The PC-9M has a top speed of 368 mph and a maximum altitude of 25,000 feet and is armed with two .50-caliber machine guns, meaning it's unlikely to catch let alone shoot down a Russian Tu-160 bomber, which can reach speeds of Mach 1.6, or about 1,228 mph, and altitudes of 60,000 feet.

A retired Air Corps pilot told the Irish Times that the PC-9M's effective altitude was only about 10,000 feet, making it "very capable of intercepting something slow-moving" like a Cessna but not much else.

In 2022, an Irish government commission recommended purchasing 24 jet fighters, but with a 2022 defense budget of just $1.3 billion for a military of only 8,200 active-duty personnel that purchase doesn't seem likely.

The issue is complicated by uncertainty about whether British fighters could legally bring down an aircraft in Irish airspace. Mulqueen said that official Irish and British statements suggest British pilots could intercept intruders but not actually shoot at them.

"Consequently, actors seeking to attack the UK have a coherent rationale to devise a secondary list of high-value targets over Ireland, so that they can mitigate the risks of RAF interception over Irish airspace," Mulqueen told Insider.

Sinn Fein — Ireland's main opposition party — has only said that it wants more information about the defense agreement before deciding whether to oppose it. Should Sinn Fein take power in the future, it would be responsible for Ireland's security, including its air defense.

Ultimately, Ireland, an EU member-state, will have to decide whether to participate in European defense. Given the state of the Irish military, that could mean even more cooperation with the UK.

"It wasn't that long ago that our neighbor was oppressing us," defense correspondent Sean O'Riordan wrote in a recent opinion piece for the Irish Examiner. "Now it's our protector, because we took our eye off the ball and effectively surrendered our neutrality by penny-pinching on our own defense."

Michael Peck is a defense writer whose work has appeared in Forbes, Defense News, Foreign Policy magazine, and other publications. He holds a master's in political science. Follow him on Twitter and LinkedIn.