Naval chiefs have pledged to protect HMS Queen Elizabeth from the “eye-watering” threat of Russian submarines as the aircraft carrier is set to sail for the US to land fighter jets on its flight deck for the first time.

The 65,000-tonne carrier is expected to leave Portsmouth Naval Base at about 6pm on Saturday to cross the Atlantic for its trip to carry out flight trials and to visit New York.

Commodore Andrew Betton, commander of the UK Carrier Strike Group, said that the carrier would be provided full protection in the face of threats from Russia.

He said: “Russian submarines are more active in the North Atlantic than they have been since the Cold War and we take that very seriously, the ship will be well protected as she makes her transit across the Atlantic.

“We will seek to operate professionally and within the standard laws of the high seas operating in international waters going about our business.

“We are not seeking confrontation, we are heading to the east coast of the United States to conduct trials.”

Captain Jerry Kyd, the carrier’s commanding officer, said: “The increase in Russian activity we have seen in the last couple of years is frightening and for national security reasons it just underlines why we need to maintain a balanced, strong and able, capable fleet.

“It’s been quite eye-watering what we have seen in the last couple of years.”

During its trip, the warship will embark two US F-35B test aircraft based at Naval Air Station Patuxent River, Maryland, which are expected to carry out 500 landings and take-offs during the carrier’s 11 weeks at sea.

Capt Kyd said: “This deployment to the United States will be another first for my ship.

“Crossing a major ocean with 1,500 sailors, aircrew and marines embarked and the spectre of the first F-35B Lightning landing on the deck in September is very exciting for us all.

“It has been an incredible journey since we left Rosyth just over a year ago and we are all looking forward to this next seminal chapter in HMS Queen Elizabeth’s life.”

He added: “People are looking forward to seeing the jets because we have been talking about them for flipping years.

“There’s a lot of excitement on board.”

Defence Secretary Gavin Williamson said: “HMS Queen Elizabeth is a true statement of our national power and the whole country can be proud to see this magnificent symbol of our engineering prowess and international ambition leaving port to sail on to the world stage.

“Her voyage to America not only shows her global reach but strengthens our special relationship with the US forces who we have worked hand-in-hand with on this iconic programme.

Able Seaman Ryan Whatmore
Able Seaman Ryan Whatmore polishes the name board of HMS Queen Elizabeth (Andrew Matthews/PA)

“As she sails along the east coast of the USA, she will signal our determination to keep fighting alongside our allies in all corners of an ever more complex and uncertain world.”

The honour of landing the first of the training jets on to the carrier will go to one of three British pilots taking part in the US deployment.

They are a Royal Navy commander, an RAF squadron leader and a civilian test pilot accompanied by a major from the US Marine Corps.

Cdre Betton added: “These first F-35B embarked trials in a UK aircraft carrier are not only key to future operational success but represent an iconic moment for the modern Royal Navy.”

On leaving Portsmouth Naval Base, HMS Queen Elizabeth will carry out tests in UK waters before heading across the Atlantic to the US where as well as the tests, she will visit New York.

She will be joined by support ship RFA Tiderace and Plymouth-based Type-23 frigate HMS Monmouth as well as Merlin MK2 helicopters from 820 Naval Air Squadron, RNAS Culdrose, Mk 4 Merlins from 845 Naval Air Squadron, RNAS Yeovilton, and Royal Marines from 42 Commando, Plymouth.

F-35 stealth fighter
The F-35B supersonic jets are based in Norfolk (Cpl Tim Laurence/MoD/PA)

The first of the UK’s joint Royal Navy and RAF F-35B supersonic jets arrived from America in June and are based at RAF Marham in Norfolk.

Testing with these British aircraft is expected to take place on board HMS Queen Elizabeth next year.

She has already undergone training with helicopters which have carried out more than 1,000 take-offs and landings.

The carrier is expected to embark on its first operational deployment in 2021.