Fifteen Scottish Labour MPs rebelled against the government in a crucial vote on Trident in the Commons.
MPs at Westminster backed government plans to renew the nuclear weapons system, by 409 votes to 161.
However, Prime Minister Tony Blair needed the support of the Tories as 87 Labour MPs voted against ministers.
All six SNP MPs and 12 Scottish Lib Dems also voted against the motion, meaning that the majority of Scottish MPs rejected Trident's replacement.
The submarine fleet which carries the Trident weapons system is based at HMNB Clyde at Faslane.
MPs had been asked to back plans to upgrade the fleet.
Ministers claimed the planning process was so long that decisions need to be taken now so that new systems could be in place by 2024.
Have your say on Trident
Critics accuse them of rushing into a mistake which could cost £25bn.
One Labour rebel, North Ayrshire and Arran MP Katy Clark, said she did not think spending £20bn on "developing new, more destructive, forms of mass destruction" could be justified.
She said that it was a whipped vote and she suspected there were Labour MPs who did not rebel but did not agree with the government policy.
"I think it is important for the Labour Party and I think it is important for the people of this country that MPs voted with their consciences," Ms Clark said.
SNP leader Alex Salmond said: "The majority of Scottish MPs voted against Trident yet Scotland gets Trident.
"Labour have been inextricably damaged tonight, even resorting to sending known anti-nuclear members on foreign jaunts to ensure the replacement of Trident was voted through.
Rebel Labour MPs
"Why on earth would people in this House want to put the nuclear weapons in a country which could shortly be independent?"
Scottish Greens speaker on nuclear issues Chris Ballance MSP said: "Ministers have not even specified under which circumstances these illegal weapons would be needed, yet they are prepared to waste £80bn on a Trident replacement.
"This money could and should be put to any number of better uses such as fighting the real threat to the UK, climate change."
Even though defence is a reserved issue, nuclear weapons could well become an issue in the Holyrood elections which are now just 50 days away.
TRIDENT MISSILE SYSTEM
Earlier in the day demonstrators climbed onto the roof of the Scottish Parliament as part of their protest over the Trident vote.
Five protesters were arrested at Holyrood and another four were detained at the Faslane naval base after they tried to block the entrance.
Two Scottish members of the UK Government - deputy Commons leader Nigel Griffiths and ministerial aide Jim Devine - resigned those positions so they could oppose the move.
Mr Griffiths, the Edinburgh South MP, told the Commons during the Trident debate that Britain must lead the world in eradicating the nuclear threat.
He said that after much reflection he could not bring himself to vote with the government.
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