Theresa May insists Trident nuclear system is 'effective' despite a missile veering off course near Florida
The Sunday Times reported that a Trident II D5 missile - which when armed with nuclear warheads has the capability to kill millions - failed after being launched from a British submarine off the coast of Florida in June last year.
Sources told the Times that the missile had veered off in the direction of America after being fired from the submarine.
While previous successful tests have been made public, a "news blackout" was imposed on this test after the missile failed to successfully meet its target.
Business Insider on Monday asked a spokesperson for the Prime Minister Theresa May whether the prime minister was satisfied that the fault with the missiles had been corrected.
"I don't accept the premise of the question," the spokesperson said.
"We have been clear the submarine and the crew have been tested and certified. That was the purpose of the operation. What was also clear is that the capability and the effectiveness of the trident missile are unquestionable."
The spokesperson said that the submarine and its crew had been successfully tested in a planned "demonstration and shakedown test."
When asked whether the missile itself had been successfully tested, the spokesperson insisted that it was not government policy to go into "specifics" about the test.
However, the current government has gone into details about previously successful tests. In 2014, then Defence Minister Philip Dunne told a defence industry conference that: "Last week I was off the coast of Florida embarked on USS West Virginia to witness a test firing of two Trident 2 D5 missiles.
"This successful test demonstrated once again that the Trident remains a credible and reliable deterrent."
Last June's failed test took place within weeks of a parliamentary vote on renewing Trident. Labour will today call on the government to face questions in parliament about the test.