Today, states routinely deploy elements of their armed forces on the territory of other states within the framework of international military cooperation or international military operations carried out with the receiving state’s consent (crisis management operations). It is in the interest of the states sending their forces abroad (sending states), as well as the states receiving these foreign forces with their consent (host states), that the legal position of the visiting forces is abundantly clear. Absent a universal convention covering the status of visiting forces, states and international organizations regularly enter into specific agreements and arrangements setting out the rights and obligations of these forces. These international agreements are part of the international law on military operations and are typically referred to as Status of Forces Agreements (SOFAs). Clearly, SOFAs will not be concluded where armed forces have entered another state’s territory without its consent, e.g., in an armed conflict situation. The legal status of the troops operating on hostile territory is then based on international humanitarian law, in particular the law of belligerent occupation. This specific field of law does not apply between allied states fighting a common enemy. Yet, the presence of a vast number of foreign troops has a marked impact on host states. Not surprisingly, the first set of bilateral agreements that today would qualify as SOFAs were concluded in World War I between a number of Allied states. Drawing from long-standing international practice, the agreements all focused on the exercise of criminal jurisdiction over the visiting forces and granted the sending states exclusive jurisdiction over their service members operating on the territory of other Allied states. During and after World War II, SOFAs evolved into more elaborate instruments covering a wider array of topics of interest to the states involved, such as claims and taxes. The core element of all these SOFAs, however, continued to be the exercise of criminal jurisdiction by either the host states or the sending states over service members of the visiting forces and over associated civilians, such as family members and contractors. States and international organizations in charge of crisis management operations regard SOFAs as an essential requirement to temporarily station armed forces abroad. Consequently, failure to come to an adequate agreement with host state authorities may hamper deployment of the troops or lead to termination of an ongoing operation, as happened in Iraq in 2011, when the United States and Iraq could not agree on the terms of a new SOFA for the US troops stationed in Iraq.
