Drew, D. M. & Snow, D. M. (1988). Making Strategy: an Introduction to National Security Processes and Problems. Maxwell Air Force Base: Air University Press.
The greatest power of the Congress is that of "the purse." Under Article I, Section 8, Congress has the power to raise revenue; under Article I, Section 9, Congress has the power to determine how those funds are spent. This power is the greatest restraint on the President's power over national security. With it, the Congress can refuse to approve the spending of money on certain weapons programs or on foreign aid to certain countries. Or, Congress can refuse to spend the amount asked for by the President on certain items, or it can even require that the President spend more money than asked for (Drew & Snow, 1988, pp. 73-74). The exercise of such power can severely hamper the President in implementing desired policies and is the most effective method of curbing policies unpopular with by the majority of Congress.
The status of the National Security Advisor has evolved since 1947 to that of a presidential advisor whose influence rivals that of members of the cabinet (Destler, 1980, p. 575). During the first term of President Nixon, National Security Advisor Henry Kissinger exercised more real power in foreign policy than did the Secretary of State. He made specific decisions concerning foreign policy, excluded State Department officials from certain back-channel negotiations, and became the Nixon Administration's prime public foreign-policy spokesman (Destler, 1980, p. 580). President Carter made the National Security Assistant a cabinet-rank official. The conflict between his NSA, Zbignew Brzezinski, and his Secretary of State, Cyrus Vance, eventually became so serious that the Administration was unable to formulate a coherent foreign policy. The two men held very divergent views on foreign policy and President Carter never made clear which views reflected his own; consequently, there was no evident directi