The United States urgently withdrew all 12 B-1 bombers from RAF Fairford in England over the weekend over fears of an Iranian drone attack, according to officials quoted by The Wall Street Journal.

President Donald Trump confirmed the move on Monday. “They didn’t fly out by accident,” he said. “There were some threats, and rather than tempting the enemy, we’ll capture the enemy and beat the enemy, but why should we leave them there?”

A Pentagon official said the bombers had returned to their home stations in the US. The base had been used for American strikes on Iran.

British authorities said last week they had foiled a suspected terror plot near the base. Five men arrested near Fairford were released on bail. A sixth man, a dual British-Iranian national, was also released on bail. Iran has denied involvement.

Trump declined to say whether Iran had smuggled drones into the UK. “I can’t tell you that, but if they did, they will suffer greatly,” he said. The UK government declined to comment on the US operational decision.