Cutting back on military training to save cash would be "the falsest of all false economies", a former member of the top brass has warned.
Lord Stirrup, an ex-chief of the defence staff and independent crossbencher, argued that "challenging, rewarding and exciting" instruction for troops was vital to the retention of personnel, on which the capability of the armed forces depended.
He sought government assurances as ministers were again tackled in the House of Lords over the threat of further defence cuts.
As well as rumours about possible reductions to the strength of the Army, there have been concerns about the future of armoured vehicle programmes and suggestions that amphibious assault ships HMS Albion and HMS Bulwark could be axed alongside the loss of 1,000 Royal Marines.
Lord Stirrup said: "Our future military capability depends on retaining sufficient talented and experienced personnel.
"That retention in turn depends on offering those personnel sufficiently challenging, rewarding and exciting training.
"Can the minister reassure the House that, in its search for savings, the Ministry of Defence will not be looking to cut back in this area, which would be the falsest of all false economies?"
Defence minister Earl Howe said: "The challenge, when looking for efficiencies rather than straightforward savings, is to achieve the same or a better level of outputs with the money available.
"I can tell him that, while training is of course under the spotlight, what we do not want to do is to dilute or degrade the quality of that training for those whose standards we set great store by."
Lord Howe also said reports around the national security capability review had "created a deeply unhelpful atmosphere of uncertainty for many of our service men and women".
He again insisted no decisions had taken.
Former Royal Navy chief and Labour peer Lord West of Spithead said blaming press speculation was "slightly disingenuous".
He said: "These clearly are things that are being looked at in that arena, and that causes a great deal of worry.
"There is no doubt that the continual downward pressure on defence is having an impact on morale."
Former army chief and independent crossbench peer Lord Dannatt argued a modest rise in the defence budget "would have an inevitable upward boost to morale".
Lord Howe said: "There are many of us who wish the defence budget were larger but every department of government has to live within its cash-limited means."