A toll on the transportation of nuclear warheads in Scotland could raise up to £85m, according to the Nationalists.
The Trident submarine fleet is based at Faslane on the Clyde
The Scottish National Party's leaders say they will seek to impose a levy on Trident if the party leads the Scottish Executive after May's election.
But the plans were dismissed as a diversionary tactic by Labour.
Armed Forces Minister Adam Ingram questioned the legality of such a move and said taxpayers would end up footing the bill.
The SNP wants to impose a £1m toll on every nuclear weapon which is brought into Scotland.
SNP leader Alex Salmond said the "Trident toll" would use devolved powers over local taxation.
The scheme would aim to raise £85m a year, which he said was Scotland's share of the cost of Britain's nuclear weapons.
"I believe that most Scots would rather see the government spend money making Scotland a safer, healthier and fairer country than wasting it on nuclear weapons," he said.
"This Trident toll will be a powerful new deterrent, and we hope will make the UK Government think again about bringing a new generation of nuclear bombs to Scotland's shores."
The Trident submarine fleet is based at the Faslane Naval Base on the Clyde.
However, Mr Ingram told the BBC's Politics Show that there were questions over the legality of the SNP's proposals.
"The other aspect is that I thought the SNP policy was one of total opposition to Trident, and to the nuclear civil programme as well," he said.
"What they are effectively now saying is that it is going to be a cash crop.
"Is it a principle or is it a way of making money? They have got to make their minds up."
He added that the cost would be borne by taxpayers as the money would come out of defence expenditure.