Raffaello Pantucci

LONDON — The leaking of sensitive information about the investigation into Monday’s terrorist attack on the Manchester Arena, including forensic images of bomb apparatus, to United States media caused dismay and anger among British officials. The prime minister, Theresa May, went so far as to raise the issue directly with President Trump when they met at Thursday’s NATO conference in Brussels.

To modify George Bernard Shaw’s maxim, Britain and America appear to be two countries divided less by a common language than by common secrets. While British investigators jealously guard detailed information about their operations, seeking to run their leads to ground before they are exposed to view, their American counterparts seem more willing to put what they know directly into the public domain.

The Anglo-American security relationship has deep roots. Intelligence sharing and cooperation sits at its heart. Forged in history, it has deepened over time through a shared assessment of the threats they face around the world. A key part of this is countering terrorism, a mutual threat that our two countries work closely together to fight. And yet, in fighting it, they have different approaches.

The current tensions over Manchester are the latest public expression of an issue that has arisen before. In May 2012, British intelligence officials were exasperated when their role in an operation to disrupt a plot by Al Qaeda in the Arabian Peninsula — to repeat the 2009 underwear bomber plot with a more sophisticated device — was revealed. Before that, after the July 7, 2005 bombings in London, information about the nature of the bombs was leaked to the press by American sources early in the investigation. The chief of London’s Metropolitan Police at the time, Ian Blair, made a connection between that incident and the Manchester leak.

“I’m afraid it just reminds me exactly of what happened after 7/7,” he told the BBC, “when the U.S. published a complete picture of the way the bombs in 7/7 had been made up.” In 2005, he was concerned both about the impact of the images on victims of the bombing, and about how the disclosures could complicate the job of his officers investigating what had been the most serious Qaeda-inspired attack on Britain to date.

The frustrations have gone beyond the leaking of information being gathered after an attack. Back in 2006, British and American authorities disrupted the most extensive Qaeda plot they’d seen. Codenamed Operation Overt, the plan was to send a wave of up to eight suicide bombers on flights from Britain to North America using sophisticated liquid explosives they could smuggle on board. This is the root of the liquid ban on planes we still face today.

In close cooperation with their American counterparts, British authorities had been watching the cell, coordinated by a British Pakistani named Rashid Rauf who had risen up Al Qaeda’s ranks, for some time. They had discovered a bomb factory in East London where the group was making its devices. The moment was approaching to disrupt the plot, but the British authorities wanted to monitor it further to ensure they would sweep up the full network and have evidence that could be used in court.

But when the American authorities thought that someone connected to the network had managed to get onto a plane, they used their network in Pakistan to get Mr. Rauf picked up. This forced Britain’s hand. Such was the rush to action that unarmed surveillance officers had to step out of the shadows to grab the suspects before news spread about Mr. Rauf’s arrest.

One reason behind the divergence between British and American counterterrorism operations is that the British authorities prefer to watch and wait, gathering as much information as possible before moving into action. American agencies prefer a more aggressive approach to disrupting terrorist networks and plots. In part, this is a product of the legal system: Intelligence agencies in Britain closely guard the information they collect and do not usually allow it to be used in a court of law. This was visible during the subsequent trials of the Overt case, where prosecutors had to go three rounds with two hung juries before they were able to convict; one of the key figures was cleared and released notwithstanding his deeply suspicious links.

There are deeper cultural issues, too. This week, the government’s assessment of the threat of a further terrorist attack has led to the deployment of armed soldiers on the streets of Britain’s cities. This is something that would likely pass unnoticed in the United States, but it has caused great consternation here. British security officials are also uneasy about the number of American counterterrorism investigations that use undercover agents who often appear to act as agent provocateurs; in the British view, such operations would be regarded as entrapment by courts.

These tensions in the relationship seem to have intensified under the Trump administration. Some British counter-terrorism experts express concern that Mr. Trump’s rhetoric of aggressive confrontation may serve to bolster the very narrative of civilizational conflict the extremists use. The ties that bind Anglo-American intelligence cooperation are firm; the difficulty is how to maintain trust after this transatlantic spat. We face a common threat, and it would be dangerous to take for granted our common front in fighting it.