The United States is a party to numerous security agreements with other nations. The topics covered, along with the significance of the obligations imposed upon agreement parties, may vary. Some international security agreements entered by the United States, such as those obliging parties to come to the defense of another in the event of an attack, involve substantial commitments and have traditionally been entered as treaties, ratified with the advice and consent of the Senate. Other agreements dealing with more technical matters, such as military basing rights or the application of a host country's laws to U.S. forces stationed within, are entered more routinely and usually take a form other than treaty (i.e., as an executive agreement or a nonlegal political commitment). Occasionally, the substance and form of a proposed security agreement may become a source of dispute between Congress and the executive branch. In late 2007, the Bush Administration announced its intention to negotiate a long-term security agreement with Iraq that would have committed the United States to provide security assurances to Iraq and maintain a long-term military presence in that country. This announcement became a source of congressional interest, in part because of statements by Administration officials that such an agreement would not be submitted to the legislative branch for approval. Congressional concern dissipated when U.S.-Iraq negotiations culminated in an agreement that did not contain a long-term security commitment by the United States, but instead called for the withdrawal of U.S. forces from Iraq by December 31, 2011. On May 2, 2012, President Barack Obama and President Hamid Karzai signed the Enduring Strategic Partnership Agreement Between the United States of America and the Islamic Republic of Afghanistan. Under the terms of the Agreement, the parties pledge to work cooperatively in a number of fields, including to promote shared democratic values, advance long-term security, reinforce regional security, advance social and economic development, and strengthen Afghan institutions and governance. Additionally, the Agreement provides that the United States and Afghanistan shall initiate negotiations on a Bilateral Security Agreement (with the goal of concluding such an agreement within a year), which is intended to replace the existing agreement relating to the status of military and civilian personnel currently in Afghanistan. It is likely that future disputes will arise between the political branches regarding the entering or implementation of international security agreements. Regardless of the form a security arrangement may take, Congress has several tools to exercise oversight regarding the negotiation, form, conclusion, and implementation of the agreement by the United States. This report begins by providing a general background on the types of international agreements that are binding upon the United States, as well as considerations affecting whether they take the form of a treaty or an executive agreement. Next, the report discusses historical precedents as to the role that security agreements have taken, with specific attention paid to past agreements entered with Afghanistan, Germany, Japan, South Korea, the Philippines, and Iraq. The report discusses the oversight role that Congress exercises with respect to entering and implementing international agreements involving the United States.