Fifteen campaigners were apprehended on the base's main runway after breaking through a perimeter fence.
The Ministry of Defence said the protesters got through a hole which they had made in the fence at the Suffolk air base at about 11am.

An MoD spokesman said the group, thought to be students from the Cambridge area, were arrested shortly after entering the base.

He said: "The protesters did cause damage to the perimeter fence by getting through a hole which they made themselves.

"In getting on to the site there was a breach of security. There was no further breach of security after that."

The protesters were detained by U.S. military police, who handed them on to their MoD counterparts.

They were questioned at police stations in Bury St Edmunds, Newmarket, Stowmarket and Mildenhall.

No charges were laid, but all 15 were later released on police bail to report back in 21 days.

Mildenhall houses the U.S. Air Force's 100th Air Refuelling Wing giant.

Its sister base at nearby Lakenheath houses US fighter-bombers.

The two bases are among the biggest U.S. airbases outside the United States mainland.

Aviators from both bases have seen action in most major conflicts involving the US in recent years.

The bases are regular targets for demonstrations by peace protesters.