Four American B-52 long range bombers have touched touch down in the UK as tensions with Russia remain high.
The planes arrived at RAF Fairford in Gloucestershire on Friday morning as part of a planned Bomber Task Mission.
The jets took off at 2am on Friday, refueled in Nova Scotia and will conduct drills with NATO allies.
One former defence official claimed the bombers could easily conduct missions in eastern Europe and Russia from the base if needed amid reports of the mass of Russian troops on the Ukrainian border.
Amid the heightened tensions with Russia, the official told The Daily Telegraph: “Is this aligned to current tensions? Yes and no.”
They added: “From Fairford they could operate against a range of targets: troop concentrations in southern Russia and Belarus, Moscow/St Petersburg, even the naval bases in the White Sea.
“In 1991 they hit Baghdad from Fairford, flew on to Diego Garcia, refuelled and rearmed, bombed Baghdad again on the way back and returned to Fairford.”
A statement from the US Air Force stated: “B-52 Stratofortress aircraft, support equipment, and personnel from the 5th Bomb Wing, Minot Air Force Base, North Dakota, arrived at RAF Fariford, England, today to execute the long-planned Bomber Task Force mission, a regularly scheduled U.S. European Command and U.S. Strategic Command joint mission series.
“En route to RAF Fairford, US Bomber Aircraft integrated with British Typhoon aircraft and Portuguese F-16s currently assigned to NATO’s Icelandic Air Policing mission. Bomber aircraft also integrated with British Joint Terminal Attack Controllers (JTAC) to conduct bilateral Close Air Support training.
“The mission focused on enhancing readiness and interoperability for the controllers responsible for coordinating airstrikes to support ground forces.
“Regularly integrating with our allies improves our cooperation and operational capacity, capability and interoperability.
“Occurring since 2018, bomber rotations through Europe maintain our readiness to execute a wide variety of missions across two continents, sustaining peace through deterrence."
The arrival of the bombers comes after Joe Biden warned US citizens they should leave Ukraine.
Although the UK, US and France have held talks with Russia, Mr Biden said the situation could change rapidly.
He said: “American citizens should leave now.
"We’re dealing with one of the largest armies in the world. It’s a very different situation and things could go crazy quickly."
The US President also said US troops would not be used to rescue American citizens from Ukraine if Russia did invade the country.