Britain will test fire a nuclear missile for the first time in eight years.
A warning was issued to shipping that a test would be carried out as HMS Vanguard, a 16,000-tonne Trident submarine, arrived in the Atlantic.
The test, which will involve a dummy warhead, will be carried out by Feb 4 around 90km off Florida’s east coast, with a range of 5,900km.
The last time the UK fired a nuclear weapon was in 2016, when a Trident II D5 missile veered off course while being tested off the coast of Florida.
As first reported by The Sun, the missile firing will be the last test before the £4 billion submarine re-enters service as part of the UK’s nuclear deterrent fleet, having been in refit in Plymouth for seven years.
During its refit last year, it was discovered that a nuclear engineer glued broken submarine bolts back together in an “unforgivable” error.
The unsatisfactory repairs to HMS Vanguard’s cooling pipes were discovered after a bolt fell off whilst being tightened during checks inside the reactor chamber.
It led to Ben Wallace, the then defence secretary, holding a phone call with the chief executive of Babcock, the defence contractor which had glued the bolt back on, demanding greater transparency.
Although such tests are planned in advance and are not a direct response to geopolitical activities, it comes as the crisis in the Red Sea has intensified.
Earlier this week, Grant Shapps, the Defence Secretary, met with his US defence and national security counterparts to discuss events in the region and how to tackle shared threats.
Since November, more than 30 attacks have been made on ships in the region which are there as part of Operation Prosperity Guardian, a multinational maritime task force made up of the UK, US and others, to protect international shipping in the Red Sea.
In a statement released on Thursday, Mr Shapps said: “It is completely unacceptable that Houthi activity in the Red Sea is threatening freedom of navigation, damaging the global economy and risking lives.
“We have worked in lockstep with our US allies to deliver Operation Prosperity Guardian, as well as conducting proportionate and targeted strikes against the Houthis.
“As two nations who champion freedom of movement, we will not cower in the face of these attacks and we would not hesitate to take further action if required.”