About 3,000 military personnel are stationed at RAF Mildenhall, which is around 80 miles (130km) north of London.
The has found there is currently very little aircraft movement at the base, and there appears to be no additional security in place around it. The spaces from which the public can photograph aircraft remain open.
The base is mostly used for refuelling and maintenance operations – flights carrying US presidents, including Donald Trump, have often used it.
It has also been used as a staging area for aircraft and material bound for the Middle East.
Air refuelling tankers were “forward deployed” to the region during operations against Iran.
Asked about the US evacuating aircraft from RAF Mildenhall, Education Secretary Lucy Powell told Breakfast she could not comment on ongoing operational matters.
She added that “we take the security and safety of our bases incredibly seriously” and “we will always act on security intelligence when we need to”.
A US Air Force spokesperson said its aircraft “rotate between installations and operating locations for a variety of reasons including training and real world requirements”.
“US military aircraft are hosted in accordance with access, basing, and overflight agreements with our allies and partners. Due to operations security, we will not provide further information on movement of assets,” the spokesperson added.
Former UK National Security Adviser Lord Ricketts told Radio 4’s Today programme: “We are talking about an airbase which houses these large tanker aircraft. Of course, they are large targets, an airbase has a long perimeter, so they are inevitably vulnerable.”
He added: “Nobody knows at this stage what this information was. I suspect part of it is an abundance of caution.”