Alex Salmond has given a guarantee that shipbuilding will continue long-term in Scotland.
The First Minister told the Scottish Trades Union Congress (STUC) that the Royal Navy will still procure ships from the Clyde and insisted further jobs would be secured through diversification.
His address to delegates at 117th annual congress in Dundee coincided with a speech by UK Defence Secretary Philip Hammond in Glasgow, in which he warned that thousands of defence jobs will be at risk if Scotland votes for independence.
Mr Hammond said the removal of Trident will not be "quick and easy" and a currency union is "not up for negotiation", amid speculation that it could be used as a bargaining chip to keep nuclear weapons on the Clyde.
Mr Salmond said there is "no way on Earth" any UK chancellor would refuse to share the pound if it meant shouldering the entire UK debt, and was given a round of applause by delegates when he repeated his commitment to rid Scotland of nuclear weapons.
GMB Scotland delegate Alex Logan, a plater at Ferguson Shipbuilders in Port Glasgow, said: "Can I ask the First Minister to give us a guarantee that the shipbuilding industry will continue long-term in Scotland?"
Mr Salmond said: "Yes, we will. The Royal Navy will continue to order ships from Scottish yards, based on that these are the best places to produce these vessels.
"But looking at what's happened over the last 20 years and the loss of jobs that we have seen in recent months, we do need diversification as well to retain shipbuilding in Scotland at a critical mass.
"Even with the reduced defence expenditure we envisage for an independent Scotland, because we won't have Trident and a contribution towards nuclear weapons, we would be buying more in terms of procurement than we are presently.
"It would therefore be ridiculous to try and put up a defence flow barrier, and there would be no reason for it whatsoever as it would be cutting off noses to spite faces."
Independence will give Scotland the power to make its own choices, Mr Salmond said.
To a round of applause, he said: "It's true of employment, foreign affairs, the economy, welfare reform, the bedroom tax, and it's true of the removal of weapons of mass destruction from Scottish soil."
EIS delegate Helen Connor, a schoolteacher, questioned the SNP's record on delivering on its "guarantees".
"The Scottish Government gave us guarantees on class sizes," she said.
"I'm sitting with a class of 33 primary fives and I don't know many primary ones that have got 18."
Mr Salmond made several more firm pledges to delegates, including a guarantee of no compulsory redundancies for former UK Government workers in an independent Scotland.
Many of his pledges were met with scepticism by STUC delegates.
Usdaw delegate Linda MacFarlane, a supermarket worker from Hawick, said: "Is the reason you haven't published a plan B on currency because you recognise that all of the other options will lead to a period of austerity more severe than that currently being applied by Westminster?"
Mr Salmond said: "There is absolutely no way on Earth that any UK chancellor would negotiate themselves into a position in which they ended up taking the whole of the national debt.
"Therefore, in the words of the unnamed Cabinet minister, of course there will be a currency union."
Mr Salmond said his fiscal commission working group is refining its position on currency following the Treasury's announcement that it would shoulder all of the UK national debt, its refusal to share the pound, and Bank of England governor Mark Carney's currency speech in Edinburgh.
His Government will soon be making further announcements on currency and its plans for childcare, he added.