Defence Secretary Michael Fallon has appealed for Labour MPs to support the renewal of Trident.
Mr Fallon urged the party's "moderates" to ignore the views of leader Jeremy Corbyn and put "national security" first.
The call, in an interview on the BBC's Andrew Marr Show, came after Mr Corbyn underlined his unilateralist views by becoming vice-president of the Campaign for Nuclear Disarmament (CND).
The veteran left-winger has faced open criticism from frontbench colleagues for undermining the party's policy discussions by openly stating he would "never" use nuclear weapons.
Appearing on BBC One's Andrew Marr Show this morning, Mr Fallon said: "We have to take this decision now to renew our deterrent for the (20) 30s, 40s and 50s and I would appeal to moderate Labour MPs to put national security ahead of party interest here and come and join us in renewing the deterrent in the way that all previous Labour governments have done."
Mr Fallon rejected criticism that Trident is an outdated Cold War era weapon.
"It isn't a Cold War weapon, it's a weapon we use every day, every night, 24 hours a day," he said.
"We are deterring people and there are 17,000 nuclear weapons out there. We can't be sure in the 2030s, the 2040s, the 2050s, that some rogue state might use nuclear weapons against us."
Shadow international development secretary Diane Abbott conceded that the "majority of the shadow cabinet" supported Trident renewal.
"The leader of the Labour Party is opposed to renewing Trident," she told the BBC's Sunday Politics.
"As it happens I'm opposed to renewing Trident. But the majority of the Shadow Cabinet want to keep Trident.
"However, the policy is out to review. And those of us that think it will be madness to spend billions of pounds on Cold War weapons we can never use hope that the review comes up with the right answer."
Ms Abbott refused to confirm reports that Labour is ready to commit to the Nato target of spending 2% of GDP on defence, even if Trident is not renewed.
"I'm not opposed to spending some of the money released by not renewing Trident," she said.
John Woodcock, Labour MP for Barrow and Furness, the home of the shipyards that build the UK's nuclear submarines, told BBC Radio 4's World This Weekend programme that Mr Corbyn's decision to become vice president of the Campaign for Nuclear Disarmament "sends a signal" that is "at odds" with the idea that Mr Corbyn will respect the will of his party.
Mr Woodcock said there is a "cast-iron majority of support" to renew Trident and it "will go through".
But Kelvin Hopkins, Labour MP for Luton North, said he welcomed the signals sent by Mr Corbyn on the subject.
"I want to see Trident not renewed," he said.
"I want to see the existing Trident decommissioned and I think that there is a large body of opinion in the country that feels like that."