The SNP is calling for the Trident missile system to be scrapped.
They have chosen to discuss the nuclear submarines during their opposition day debate.
Conservative ministers want to renew the current arsenal at an alledged cost of £167bn.
Workers at the Faslane naval base, where the submarines are based, have in the past rased concerns over safety.
Defence secretary Michael Fallon says the weapons are essential to ensure the securtity of th eUK at a time of heightened tensions.
SNP Defence spokesperson Brendan O'Hara MP said: "Trident should not and must not be renewed. This may be the last parliamentary chance to stop this utterly awful project and the challenge is to Labour to join us and all those MPs who see the folly of it – and put a halt to it once and for all.
"The tragedy is Westminster is still hell bent on spending a huge amount of money of something useless – and the Tories want to rush through the maingate decision which will commit the UK to Trident for decades to come.
"Westminster wants to spend this indefensible amount of money on weapons designed to fight the last war. It is the UK’s ultimate virility symbol – it allows David Cameron to wield what remains of his imaginary influence – proving beyond any doubt it is not a military asset – it is a political one."
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