Britain is set to rest fire a nuclear missile in just a few days in a significant show of force towards Iran and Russia.

This will be the first time since 2016 that the UK will test fire a missile, and it comes amid warnings that the world could be edging closer to World War III.

The HMS Vanguard submarine sailed into the Atlantic earlier this week; it is expected to fire the missile off the US coast near Florida.

It is expected to launch a single unarmed missile that will fly 3,500 miles and land in the Atlantic Ocean off the coast of West Africa.

The US National Geospatial-Intelligence Agency warned shippers to expect an impact in the mid-Atlantic area.

The warning also urges those closer to the launch site to be aware as debris is expected to fall as parts of the missile are burnt out and discarded.

The warning is in place from January 30 through to February 4.

The tests are the final hurdle the £ 4 billion sub has to overcome before re-entering service as part of the UK’s nuclear deterrent fleet.

The 30-year-old sub had spent the past seven years undergoing a refit in Plymouth and has been dubbed a “colossus” by the Royal Navy.

The sub’s refit reportedly cost £ 500 million and took three years longer than expected.

The 491ft beast can carry up to 16 Trident 2 D5 missiles, each armed with warheads 20 times more potent than the weapons dropped on Japan in World War Two.

The last test, which took place eight years ago with the HMS Vengeance, failed.

The missile was due to be 5,500 miles from near the coast of Florida to a target southeast of Ascension Island.

It veered dangerously off course and self-destructed automatically.

That had been only the fifth time a Trident 2 missile had been fired this century, with the previous tests taking place in 2000, 2005, 2009 and 2012.

Trident missiles are designed to blast to the edge of space before re-entering the atmosphere and plummeting towards Earth.