The UK government is facing new questions about the failure of an unarmed nuclear missile during a test firing off the US coast last June, IBTimes UK revealed on Wednesday (1 February).

The SNP's defence spokesman at Westminster, Brendan O'Hara, disclosed that he has asked the Ministry of Defence (MoD) a dozen questions about the so called "shakedown operation".

Defence Secretary Michael Fallon told MPs that Trident submarine HMS Vengeance and its crew were "successfully certified" despite the D5 missile reportedly veering off course towards the Florida mainland.

But Fallon failed to confirm or deny whether the Lockheed Martin missile automatically diverted itself into the sea to self-destruct.

The revelation of the misfire, first reported in The Sunday Times, caused a political uproar since MPs were not informed about the operation ahead of a vote in the Home of Commons on the £40bn ($50bn) renewal of Trident.

The row was knocked off the top of the news agenda in the UK after the government lost a landmark case at the Supreme Court over Brexit.

But O'Hara has vowed to maintain the pressure on Fallon and the government over the Trident test. "They are hiding behind 'national security' and desperately trying to say nothing," he said.

"We are not letting this go, we realise there's an awful lot happen in terms of Brexit, but that's not an excuse that the government can just pretend that this never happened."

The questions include whether the missile's guidance systems was tested during the operation and at what point Fallon was informed of the misfire.

A source close to the Defence Select Committee, chaired by Julian Lewis, told IBTimes UK that the group is still deciding on their response to the incident after holding an emergency evidence session with former First Sea Lord Admiral Lord West.

Green co-leader Caroline Lucas is also planning on pressing the government with more parliamentary questions, a source close to the Brighton Pavilion MP told IBTimes UK.

Dr Jeffrey Lewis, of the Middlebury Institute of International Studies at Monterey in California, has described the D5 Trident missile as "remarkably reliable", with Lockheed Martin boasting of more than 150 successful tests in 2015.