New defence secretary Gavin Williamson has privately expressed shock at the extent of cuts due to be imposed on the MoD by the Treasury.
Mr Williamson has been told he must find a way of reducing the defence budget by £2 billion a year.
The Ministry of Defence has dismissed speculation over the nature of the planned cuts, but the government faces a backbench rebellion from angry MPs.
Defence Secretary Gavin Williamson was said to be shocked by the 'completely awful' headline proposals drawn up by military chiefs
One Whitehall source told The Times that Mr Williamson is trying to prevent the army's decimation.
The source said: 'Gavin is aware he has a huge challenge on his hands. He does not like what he came into . . . We are beginning to try and push back.
'Britain would risk becoming a global laughing stock at a time when we need defence to be our strong card post-Brexit.'
The army has a target strength of 82,000, but it is now at 77,440 and could shrink to below 70,000.
Such is the anger within the Conservative Party to the proposed cuts, one defence minister, Tobias Ellwood - who battled to save a Westminster terror attack victim - has threatened to