The East Midlands MP visited Rosyth shipyard to meet staff working on the Royal Navy’s aircraft carriers and hear their views about Scottish independence.
Alongside shipbuilding jobs on the Clyde, there are thousands of Scottish defence jobs across the country in industry, as well as employment from bases at Kinloss, Lossiemouth, and from Faslane to South Uist.
There were an estimated £300 million of sub-contracts awarded to Scottish-based companies from the carrier contract alone.
Mr Coaker said: “The jobs of thousands of Scots in our defence industry are secured by being part of the UK. They play a critical role in supporting our armed forces and helping to keep us all safe and secure.
“One thing we know beyond doubt is that leaving the UK would cost defence jobs.
“The UK Government has never awarded a contract for complex warships outside of the UK. The idea that somehow everything would carry on as it is just because Alex Salmond says so simply isn’t credible.”
Anas Sarwar, Scottish Labour’s deputy leader, said: “We know the SNP will say and do anything to win the vote, setting aside the reality of life in an independent Scotland.
“The truth is that being part of the UK is good for Scottish jobs but a Yes vote puts those jobs at risk.”