But while almost everyone appears to agree that security guarantees are an essential element of any peace deal, there is currently no consensus over what these guarantees should actually involve. At present, the emerging picture of future security guarantees appears to have four key components. European nations are expected to take the lead in providing security guarantees, with the United States playing a crucial but as yet undefined supporting role. The key question regarding the presence of foreign troops on Ukrainian soil is whether they would be given a mandate to engage in combat operations. Integration into existing European security structures will be crucial, including full coordination of the Ukrainian military with foreign partners providing the aviation and naval components of any future security guarantees.