Another plane carrying highly radioactive waste, en route to the United States, left the Highlands at the weekend amid intense security.
Armed police stood guard at Wick John O’Groats airport as the enriched uranium was loaded onto a US Air Force C-17 Globemaster transport jet.
The operation, in the face of Britain’s “severe” terrorist threat, established by the Joint Terrorism Analysis Centre and MI5, got underway at 10am on Saturday.
Police were joined by heavily armed anti-terrorism specialists arriving in vans with blacked-out windows.
Armed police and Civil Nuclear Constabulary officers guarded the convoy of two trucks, with the radioactive material contained in heavily reinforced steel flasks.
Roads surrounding the airport, which has no commercial flights on Saturday, were closed to other traffic.
After a couple of hours, with the cargo loaded, the giant jet lumbered along the runway and took off for the short hop across the Moray Firth to RAF Lossiemouth in Moray to top up with fuel because the runway at Wick is 1,712ft too short for a fully fuelled Globemaster to get airborne.
The runway was strengthened, but not lengthened in preparation for the flights in an £8million upgrade.
At Lossiemouth, the US transporter was refuelled under armed RAF guard before heading for a nuclear facility in Tennessee.
A waste deal signed last year by former Prime Minister David Cameron and ex-US President Barack Obama permitted the flights in return for medical-grade uranium to make radio isotopes for detecting cancer. It was condemned by environmentalists.
A spokesman for the Nuclear Decommissioning Authority said: “We can confirm that nuclear materials are being removed from the site ahead of its closure.
“Our priority is to comply with the regulations governing the safety and security of nuclear material.”
A spokesman for the police said: “We’re supporting a partner agency’s operation and can’t comment further.”
Independent nuclear consultant, John Large, described the materials as “pretty toxic weapons-grade stuff” that was “ticking away and doesn’t turn itself off.”
A spokesman at Wick John O’Groats Airport said: “We don’t comment on specific aircraft movements. However, all permitted movements at the airport comply with the operating protocols and requirements of the airport.”
A further 10 transatlantic runs are expected in the future.
