Although the aspirations and goals of states are often motivated by external political pressures, analysis of recent foreign policy decisions demonstrates how internal political forces can play equally crucial roles in the pursuit and execution of these objectives. Thus, it would be invalid to claim that domestic politics and the nature of regimes play minor roles in either the goals a state pursues or the means it employs to reach them. By understanding how the diffusion of power in governments affect policy decisions, one can develop increased awareness of the linkages that exist between the internal pressures of domestic politics and the external forces of foreign politics. Before discussing the impact of domestic politics on foreign policy objectives and their execution, one must first understand the different types of policies that states pursue. The foreign policy of states can be directed toward the protection and enhancement of valued possessions ("possession goals") or intended to improve the environment in which it operates (milieu goals). More specifically, possession goals pertain to national possessions where states aim to enhance or preserve one or more things they value such as territory, permanent membership in international organizations like the UN Security Council, or access to trade areas.

And while milieu goals are different from possession goals in that states that work towards achieving them are not seeking to defend or increase their possessions but instead attempting to shape conditions beyond their national boundaries, milieu goals can be seen as an indirect way of achieving possession goals. A nation that pursues a milieu goal-such as the promotion of peace through the signing of international treaties-provides clear benefits for the international community but ultimately serves to enhance its own national security by creating a safer environment where its national possessions are protected from external threats. But for many states, whether their foreign policy objectives assume the form of possession goals or milieu goals, the pursuit and execution of these goals are often constrained by the powers of domestic politics. And in the case of American foreign policy, the Constitution of the United States as well as recent history provides compelling support to this claim. American foreign policy is made through a fragmented and fractured process.

The United States Constitution states that the president shares power with Congress in the development of foreign policy. As the commander in chief, the president plays a significant role in shaping foreign policy. The president possesses the power to appoint senior cabinet members, commit troops and conduct high level talks with foreign governments. Congress, on the other hand, has the power to ratify treaties, confirm the president's appointees and approve budgetary measures. And while the president has the ability to commit troops, only Congress has the authority to declare war. Despite criticisms of the American policy making process describing it as inefficient and slow moving, the main purpose and thus benefit of the constitutional separation of power is the framework of checks and balances that safeguard against monopolization of foreign policy decision making.

But despite the provisions outlined in the Constitution outlining the separation of power between the executive and legislative branch in the formulation of foreign policy, congressional influence over foreign policy decisions waned after World War II. During the Vietnam War, the Johnson and Nixon administrations became increasingly secretive and monopolized foreign policy decision authority. Ultimately, however, the growing imbalance of influence of the executive branch in foreign policy decisions led to the creation of the War Powers Act. The Act stipulated that the president was required to report to Congress within 48 hours after the beginning of hostilities. The president could continue hostilities for a maximum of sixty days in the absence of congressional authorization and then could take 30 days more to complete withdrawal of US forces. In short, the War Power Act of 1974 allowed congress to stop war at any time by passing a concurrent resolution.

US forces could be brought home from a war or any other circumstance involving hostilities by a majority vote of both the house and senate. Despite the problematic issues of enforcement that surround it, the War Powers Act provides an example of how domestic politics-in this case congressional interests-can play a major role in the conduct of foreign policy. In terms of the prisoner's dilemma, the influence of domestic politics on foreign policy often leads to suboptimal outcomes. The US does not follow a rational actor model in regards to the formation of foreign policy. Instead, competing ideas drive foreign policy and often result in the adoption of suboptimal policies.

A recent example of this was the defeat of President Clinton's Comprehensive Test Ban Treaty by the Senate in 1999. While President Clinton and the Senate Democrats viewed the CTBT as a milieu goal intended to reduce the threat of nuclear proliferation in the international environment, Senate Republicans perceived the CTBT as a threat to American possessions-namely the primacy of US nuclear superiority and deterrence capability-and thus sought the defeat of the treaty as a possession goal. The Senate Republicans fought against the treaty because they saw it as an attempt by the US to shape the international environment at the cost of defending against and deterring security threats. Their reasoning was that dishonest states could circumvent international verification systems and conduct nuclear testing secretly or even perform tests with blatant disregard to the treaty since only their signatures and not the fear of military punishment promised their cooperation. But more importantly, the Senate Republicans argued that without the ability to test, the American nuclear arsenal could be potentially less reliable and that advances in weaponry would be stalled, thus diminishing the superior deterrence and defensive capabilities of the US against nuclear threats.

Domestic political concerns over the national defense implications of the C BTB led to the eventual defeat of the treaty. Although there are strong indications that domestic politics play a significant role in the pursuit and achievement of foreign policy goals, some critics continue to argue that the influence of domestic politics and regimes on foreign policy is minimal. According to the Realist Model, the state is viewed as the most important actor rather than the individual, and it discounts the influence of domestic politics when analyzing national interests. Under the lens of the Realist Model, the actions of states can be interpreted without reference to domestic politics or leadership. Realists argue that the interests of states transcend domestic politics and leadership change because that the broad orientation of foreign and defense policies are unchanging.

Although the realist model may be most appropriate for analyzing actions when vital interests are at stake such as in times of crises, it seems to have little explanatory power for national security policy making in times without crisis. Although the aspirations and goals of states are often partially motivated by external pressures, it is important to recognize that internal forces also play equally crucial roles in the pursuit and execution of these objectives. The decisions of foreign policymakers must take into account domestic political considerations. This fact is especially evident in the political landscape of the United States, where the separation of powers between the executive and legislative branch allows Congress to act as a counterweight to the power of the president. All states, whether their governments are democratic or authoritarian, must contend with domestic political considerations when evaluating foreign policy decision.