Jeremy Corbyn has been given a new warning he faces stiff resistance from Labour MPs over his aim to abandon Britain's nuclear deterrent.
A report by Labour's backbench defence committee dismissed the case for getting rid of the submarine-based Trident deterrent as being based on "myth, science fiction and gross inaccuracies".
The 65 page report - including evidence from former senior military commanders, current and former ministers, foreign policy experts and historians - concludes there is no evidence that unilateral nuclear disarmament by the UK would encourage other nuclear states to follow suit.
It says it would be "bizarre" for Britain to get rid of its nuclear arsenal at a time when Russian aggression meant international environment was becoming more dangerous, with the potential for regional conflicts to embroil Nato member states.
In a section that is likely to been seen as particularly provocative by the party, it lists "common myths" which, it says, have been wrongly used by the anti-Trident lobby to advance their case.
They include a "highly exaggerated" warning by shadow defence secretary Emily Thornberry that advances in anti-submarine warfare such as the development of underwater drones or cyber attacks could compromise the deterrent.
It also dismissed a compromise suggestion by Mr Corbyn the submarines could continue to operate - but without their nuclear missiles - saying it would undermine UK security and credibility without generating significant savings.
The report underlines the strength of the opposition to the Labour leader who has made clear he his determined to reverse the party's current support for maintaining the deterrent.
Many MPs have already indicated that they intend to vote with the Government when the Commons debates the renewal of the submarine fleet later this year.
The committee chair John Woodcock said: "Voting to maintain the UK's nuclear deterrent by replacing its ageing submarines is a vital strategic decision which must be based on accurate information rather than the myths, science fiction and gross inaccuracies that have dominated the debate of late.
"This report is based on the widest available evidence, collected from the leading experts in their fields and will hopefully be of use to Labour members and MPs in the face of sustained efforts to muddy the waters with inaccurate figures and Buck Rogers-style scare stories dressed up as military expertise."