After his opposite number Vernon Coaker reaffirmed Labour’s commitment to maintaining the Clyde-based nuclear deterrent, Mr Fallon asked how this could be achieved when the SNP – predicted to hold the balance of power after 7 May – was so set against it.
He told the BBC’s Daily Politics election debate on defence and security: “How can you get renewal of Trident if you are a minority Labour government? You can’t get power on your own, you are being propped up by the SNP.
“How can you possibly get it through? When Nicola Sturgeon has said it’s an absolute red line.”
Mr Coaker insisted Labour would not negotiate on the country’s national security, before asking him: “How would the Conservatives vote?”
Mr Fallon replied: “You want to leave it to the uncertainty of a 10 o’clock vote, not knowing which MPs are going to vote which way? This is too important to be left to a late-night vote in the House of Commons.”
Pressed to clarify why Labour could not count on the support of the Conservatives, Mr Fallon went on: “Because you’d have uncertainty. The way to be absolutely sure about our nuclear defence is to vote Conservative, have the four ballistic missile submarines.”
Trident is a system of submarine-based nuclear missiles, based on four boats. At any time at least one of them is at sea, on patrol, somewhere in the world. One of the four Vanguard-class submarines has been constantly on patrol since the system came online in 1994.
While the missiles are expected to be useful for several more decades, the four submarines are coming to the end of their life. The Vanguard-class was designed to operate for 25 years – taking the boats to the mid-2020s.
A Conservative Party spokesman said: “Ed Miliband can only get into No 10 with the backing of the SNP – and Nicola Sturgeon’s made it crystal clear that Trident’s a red line issue.
‘It’s also no secret that 75 per cent of Labour candidates are also against renewing our nuclear deterrent. Vernon Coaker again was unable to rule out any deals with the SNP. The only way to guarantee a continuous at-sea nuclear deterrent is to vote Conservative on 7 May.”