Home Secretary Amber Rudd has said she is irritated with the US for releasing information about the Manchester bomber before UK police would have liked.
Ms Rudd said the British had wanted to control the flow of information to "keep the element of surprise".
She told BBC Radio 4's Today programme she had been very clear with Washington "that it should not happen again".
Ms Rudd said the Manchester-born bomber Salman Abedi had already been on the radar of the British security services.
She claimed the 22-year-old, born to parents of Libyan origin, "was known up to a point" in the UK.
Ms Rudd spoke out as the government raised the terrorism threat level to "critical" - the highest possible rating - on Tuesday amid fears another attack was imminent.
She said this meant the police would have 3,800 soldiers to call on and equipment for "as long as we need them".
The measures follow Monday night's attack at Manchester Arena, which killed 22 and injured 59.
Counter-terrorism detectives have spoken in the past about how important it sometimes is for them that names of suspects do not make it into the media. They say a delay of around 36 hours, before the public know who they are investigating can allow them to arrest known associates of the suspect before they know police are looking for them.
Information about the bomber's identity first emerged in the US - with American TV networks CBS and NBC naming Abedi as the suspect.
More:
http://www.bbc.co.uk/news/election-2017-40026413
