The malfunction came just weeks before the House of Commons was asked on July 18 to approve the replacement of the ageing submarines that carry Britain's nuclear arsenal. May was not prime minister at the time of the test, but she took office shortly before the vote and successfully appealed to lawmakers to approve the 41 billion (47 billion euro, USD 50.7 billion) project.
Britain is one of only three nuclear-armed NATO nations, along with the United States and France.
An authoritative report said an unarmed Trident II D5 missile had veered in the wrong direction towards the US coastline when it was launched from a British submarine, HMS Vengeance, off Florida, last June.
MPs voted last summer to spend around £40 billion on replacing Trident, having absorbed Mrs May’s assertion that she would be willing to authorise a nuclear strike that could mean the deaths of 100,000 people.
The US Navy is test-firing and upgrading its arsenal of Trident II D5 nuclear-armed submarine launched missiles designed to keep international peace -- by ensuring and undersea-fired second-strike ability in the event of a catastrophic nuclear first strike on the US.
Firing from the Atlantic Ocean off the coast of Florida several months ago, a specially configured non-armed “test” version of the missile was fired from the Navy’s USS Maryland. This was the 161st successful Trident II launch since design completion in 1989.
The Trident II D5 missile is deployed aboard U.S. Navy Ohio-class submarines and Royal Navy Vanguard-class to deter nuclear aggression. The three-stage ballistic missile can travel a nominal range of 4,000 nautical miles and carry multiple independently targeted reentry bodies.
The U.S. and UK are collaboratively working on a common missile compartment for their next generation SSBNs, or ballistic missile submarines.
"The Trident D5s carry three types of warheads: the 100-kiloton W76/Mk-4, the 100-kiloton W76-1/Mk-4A, and the 455-kiloton W88/Mk-5 warhead, the highest-yield ballistic missile warhead in the U.S. arsenal."
The Trident II D5, first fired in the 1990s, is an upgraded version of the 1970s-era Trident I nuclear weapon; the Trident II D5s were initially engineered to serve until 2027, however an ongoing series of upgrades are now working to extend its service life.
The missiles are also being planned as the baseline weapon for the Ohio Replacement Program ballistic missile submarine, a platform slated to serve well into the 2080s, so the Navy wants to extend the service life of the Trident II D5 missiles to ensure mission success in future decades.
Under the U.S.-Russia New START treaty signed in 2010, roughly 70-percent of the U.S.’ nuclear warheads will be deployed on submarines.