22 U.S.C. § 292

(a) Authority of Secretary of State The Secretary of State is empowered to acquire by purchase or construction in the manner hereinafter provided, within the limits of appropriations made to carry out this chapter, by exchange, in whole or in part, of any building or grounds of the United States in foreign countries and under the jurisdiction and control of the Secretary of State, sites and buildings in foreign capitals and in other foreign cities, and to alter, repair, and furnish such buildings for the use of the diplomatic and consular establishments of the United States, or for the purpose of consolidating within one or more buildings, the embassies, legation, consulates, and other agencies of the United States Government there maintained. The space in such buildings shall be allotted by the Secretary of State among the several agencies of the United States Government. (b) Payments from other than appropriated funds for acquisition of property Payments made for rent or otherwise by the United States from funds other than appropriations made to carry out this chapter may be credited toward the acquisition of property under this chapter without regard to limitations of amounts imposed by this chapter. (c) Authorization for improvements and construction The Secretary of State may improve or construct facilities overseas for other Federal departments and agencies on an advance-of-funds or reimbursable basis if such advances or reimbursements are credited to the Embassy Security, Construction, and Maintenance account and remain available until expended.