LONDON — After Monday night's suicide attack in Manchester, in which at least 22 people were killed, Prime Minister Theresa May raised Britain's terrorism threat level from “severe” to “critical,” suggesting that another attack was “imminent” and that the 22-year-old suspect may have been working as part of a broader network.

For the first time in more than a decade, soldiers were deployed to guard Buckingham Palace and several other landmarks. It is the first time since 2003 that Britain has deployed armed troops to protect its streets.

On Wednesday, soldiers were seen taking up positions outside Downing Street, Parliament and Westminster.


Soldiers arrive near Buckingham Palace. (Jack Taylor/Getty Images)

The Changing of the Guard ceremony at Buckingham Palace was canceled. (Dominic Lipinski/PA via AP)

A soldier joins a police officer outside Buckingham Palace. (Philip Toscano/PA via AP)

With the terrorism threat at its highest level, tours of Buckingham Palace and Wednesday's Changing of the Guard ceremony were canceled, much to the dismay of tourists and many social media users.

Although some appeared disgruntled at the beefed-up security, others said the new measures made them feel more safe.

“We do feel safer, and I think it's probably a deterrent,” said Clive Thomson, 46, as he glanced over his shoulder at a soldier standing inside the gilded railings of Buckingham Palace. Referring to the attack in Manchester, he said, “For them to target children, that's the lowest of the low.”

Although Thomson could spot only two soldiers, he said the number of armed officers outside the queen's London residence had increased significantly since Tuesday. “There's only two army, but when you add up the number of armed people, I think we counted a dozen people with guns. And there's the helicopter above. That's new.  That's ample.”

Jane Ritchie, 44, his partner, said the added security could become a more permanent feature.

“I think it's really good. It makes us feel safer, more visible bodies. I can see it as an ongoing thing, especially after everything that just happened.”


An armed soldier patrols outside 10 Downing Street. (Justin Tallis/AFP via Getty Images)

10 Downing Street is among the landmarks where security has been enhanced. (Lauren Hurley/PA via AP)

A soldier joins armed police officers guarding Downing Street. (Tim Ireland/AP)

“It's a very good thing, it's visibility, it's assurance,” said Geanalain Jonik, a 48-year-old tourist from Paris who was peering through the railings of Buckingham Palace. He said similar security measures have brought reassurance to the people of Paris in the wake of Islamist militant attacks in recent years. “We don't have enough policemen, and when you see soldiers and troops in the streets, it's better, it gives you the sense of feeling safe.”

At 11 a.m. Thursday, a minute's silence is to be held across the United Kingdom as a mark of respect for those who lost their lives in the Manchester attack.