The U.S. Embassy in London, after the arrest of several people over allegations of an attempt to carry out a bombing near RAF Fairford air base, has asked American citizens to exercise caution.

In a statement, the U.S. Embassy said: “U.S.-related facilities, gatherings, and organizations may face heightened risk.”

The notice added: “We remind American citizens that British authorities assess the level of the terrorism threat in this country as severe.”

In July, and following a warning from the Islamic Revolutionary Guard Corps about the use of U.S. bombers from the Fairford base, Britain said its armed forces are prepared to respond to any possible attack.

The U.S. Embassy advised citizens of that country to pay attention to their surroundings, review their personal security plans, and inform friends and family members about their safety situation.