The ability of the British armed forces to fulfil their role effectively could be limited by economic damage caused by Brexit, a parliamentary report has warned.
The June 23 vote to withdraw from the EU could inflict "significant" real-terms cuts on defence budgets, said the Joint Committee on the National Security Strategy (NSS).
Its report was critical of ministers' failure to set out contingency plans for Brexit in the NSS published along with the Strategic Defence and Security Review (SDSR) last November, accusing them of putting political interests ahead of national security.
Planning for a new security review - normally expected only once or twice a decade - should begin "immediately" to take account of the UK's changed circumstances, the committee said.
The report also took the Government to task for its stance towards China in an NSS which "highlighted economic possibilities and marginalised risks" from issues like human rights, cyber espionage and the "aggressive militarisation" of the South and East China Seas. The "overwhelmingly positive assessment of China" set out in the official strategy "may undermine the UK's global standing and reputation among its allies", the committee warned.
Last year's SDSR was underpinned by the Government's commitment, for the rest of this decade, to meet the Nato target of spending 2% of GDP on defence. This implied an annual real-terms increase of 0.5% above inflation in the Ministry of Defence budget, taking spending from £34.3 billion in 2015/16 to £38.1 billion in 2019/20.
But the report found that the referendum vote "may well affect the growth of the UK economy in the foreseeable future", with a knock-on effect on the cash available for defence.
Citing estimates by the independent Institute for Fiscal Studies that Brexit could cut GDP by 2.1%-3.5%, the cross-party committee warned of a possible £40 billion black hole in the public finances by the end of the decade.
And it said: "In that context, even if the new Government were again to commit to spending at least 2% of GDP on defence, a stagnant or contracting UK economy might mean that the defence budget would be significantly reduced in real terms."
Brexit could impact on the "aspirations and capabilities" set out in the NSS and "limit the ability of the armed forces to fulfil their role effectively", said the report.
The committee said it was "surprised and disappointed" that last year's review failed to discuss the implications for security of a possible vote to leave the EU, which it said "will arguably lead to the most radical change in the UK's place and role in the world since the withdrawal from east of Suez at the end of the 1960s".
"The failure to outline a plan to address that contingency indicates the prioritisation of political interests above national security," said the committee. "If the NSS is to be credible, it must prioritise the maintenance of national security above political expediency. Planning for a new security review, starting with a detailed analysis of the changed security environment, should begin immediately."
The committee also voiced "concern" about armed forces manpower, which it described as "inadequate bearing in mind the range, complexity and potential concurrency of tasks expected of them". And it warned that the MoD "may struggle" to meet efficiency savings totalling £9.2 billion expected from it over the next five years.