Three airbases in Norfolk and Suffolk have been buzzed by unidentified drones, the US military has confirmed.

The incidents saw 'small unmanned aerial systems' (UASs) flying above RAF Lakenheath and RAF Mildenhall in Suffolk and RAF Feltwell in Norfolk. 

The drones were spotted between Wednesday, November 20 and Friday, November 22. 

All three bases are used by the United States Air Force who have said it is unclear whether the drones were considered hostile. 

READ MORE: 'They make us a target': Anti-nuclear weapons protest takes place at RAF Lakenheath

"The number of UASs [unmanned aircraft systems] fluctuated,’ a US Air Forces in Europe spokesman told The War Zone, a defence news and analysis website. 

"They ranged in size [and] configuration. The UASs were actively monitored and installation leaders determined that none of the incursions impacted base residents or critical infrastructure."

The spokesman declined to comment on claims that flight operations were affected or the reported deployment of F-15E Strike Eagles to respond to the incident.

He added: "To protect operational security, we do not discuss our specific force protection measures but retain the right to protect the installation. 

"We can continue to monitor our airspace and are working with host-nation authorities and mission partners to ensure the safety of base personnel, facilities and assets."

A spokesman for the British Ministry of Defence said: “We take threats seriously and maintain robust measures at defence sites. This includes counter drone security capabilities.

“We won’t comment further on security procedures.”

The incident comes at a time of growing international tensions. 

RAF Lakenheath is the largest American airbase in Britain is set to store nuclear weaponry three times stronger than the Hiroshima bomb in response to the increased threat from Russia.

Russian officials have warned that western support for Ukraine could “lead to a collision between nuclear powers”.

Earlier this year documents from the Pentagon revealed plans for a new facility at the Suffolk airbase alongside equipment including ballistic shields.

Nuclear missiles were previously stationed at RAF Lakenheath until 2008 when the threat of a Cold War from Moscow ended.

The American army has revealed it is developing ammunition to shoot down drones with helicopters and tanks equipped with medium calibre rounds capable of hitting small, high-speed targets.