US Air Force says it responded to unauthorized drone activity over airbase in England

Unauthorized drone activity over an American airbase in Britain prompted a security response this week, but US and UK defense officials said Friday that the situation has been resolved.

Security forces at Royal Air Force Base Lakenheath in eastern England responded to suspected unauthorized drone activity, the US Air Force in Europe said in a statement, adding that no personnel, aircraft or infrastructure were affected.

"We continue to work closely with our host nation counterparts to ensure the safety and security of our US service members, US and host nation civilians, contractors, and all of our families," the statement said.

A spokesperson for the British Ministry of Defense said the incident has been "resolved." US Air Force security personnel responded to the reports, and the ministry was working closely with the Americans to determine what happened, said the spokesperson, who spoke on condition of anonymity to discuss sensitive security matters.

The episode means three US bases in the United Kingdom have now been affected by threats in recent weeks. Friday's response at RAF Lakenheath came just days after the US moved more than a dozen aircraft from RAF Mildenhall, another base only miles away in eastern England, because of a threat. During the relocation, RAF Mildenhall raised its alert level to FPCON Charlie, the second-highest level, which is used when an incident occurs or intelligence indicates some form of terrorist action against personnel or facilities is likely. A US official said at the time that moving the aircraft was proactive rather than reactive.

Several weeks ago, a group of men was detained after three suspicious vans were spotted traveling toward RAF Fairford, roughly 150 miles (240 kilometers) west of Mildenhall and Lakenheath. British authorities linked the plot to Iran, and the US withdrew its bombers that had been stationed at the base, which American bombers have used during decades of conflicts in the Middle East, including the Iran war. Further arrests followed, and at least three men alleged to be Iranian operatives have been charged by the US with plotting to attack RAF Fairford.

The trio allegedly helped plan and direct the September incident at the base, which came to light when police were called after a local farmer reported seeing a group of men with several white vans engaged in "suspicious" activity. A US charging document stated that a man identified as Mohammad Ali al-Hassani directed unnamed individuals to drive to the base in the vans, some of which contained barrels of fuel, and that he had earlier paid the group to buy metallic objects that could be used as shrapnel.

UK police last month charged two British men with national security offenses related to the RAF Fairford incident. One was charged with assisting a foreign intelligence service, believed to be in Iran, and another with entering a prohibited place for a purpose "prejudicial" to the UK.

Britain's domestic spy chief said in October that Iran had stepped up attempts to hit harder targets such as military sites in Britain. In an interview broadcast Wednesday, Iranian security chief Mohsen Rezaei threatened to strike US bases beyond the Middle East, including in Europe, if they are used for attacks against the Islamic Republic.

Iranian officials have previously threatened to widen the geographic scope of the conflict should the US attack again. In late September, an adviser to Iran's new supreme leader Mojtaba Khamenei publicly mused that the war could "expand even further, reaching the Indian Ocean and perhaps beyond."