The head of the armed forces has urged the Government not to make further cuts to expertise about overseas threats ahead of the mini-budget.
Operations over the last decade have "absolutely reinforced" the importance of specialist knowledge, General Sir Nicholas Houghton said.
Cuts to the Foreign Office have led to a 7% reduction in expert staff members, according to members of the defence select committee.
Asked if it would be a "concern" for the Ministry of Defence if specialist intelligence about countries like Russia diminished, the chief of the defence staff told MPs: "We should not be disinvesting in our ability to understand the nature of the world in which we might be asked to operate."
There are "areas where we would probably have some concerns", he told the committee.
Gen Houghton said new arrangements that mean the Cabinet Office effectively oversees the Strategic Defence and Security Review (SDSR) meant there would be a more "holistic" assessment.
Since the 2010 review there has been a shift from "latent threats" to "patent threats", he said.
"We are in a different position now. The threat situation has worsened but the opportunity for the betterment of the capability to mitigate threats means that we are confronted by a different set of choices."
Gen Houghton said he felt there had been "insufficient emphasis" in the groundwork of the most recent risk assessment on the potential combined impact of different security threats, which would have given a "darker picture".
But once the issue reached military top brass and the most senior officials differences were "accommodated", the committee was told.