US cautions Americans in UK to be alert after Britain raised threat level

WASHINGTON - The U.S. embassy in London has cautioned Americans in the UK to stay alert in public places, keep a low profile and review their personal security plans after British government officials said earlier that they were raising the national terrorism threat to its second-highest level.

"The recent increase in terrorist threats is driven by a rise in Islamist and extreme right-wing terrorist threats in the UK," the U.S. embassy said in a security alert on Friday.

Britain raised its national terrorism threat level to "severe" from "substantial" on Thursday after an antisemitic stabbing attack earlier in the week in north London.

The threat level indicates that an extremist attack is highly likely within the next six months.

(Reporting by Jasper Ward and Kanishka Singh in Washington)

Copyright Reuters or USA Today Network via Reuters Connect.

This story was originally published May 1, 2026 at 1:51 PM.