10 USC 2806 – Contributions for North Atlantic Treaty Organizations Security Investment
(a) Within amounts authorized by law for such purpose, the Secretary of Defense may make contributions for the United States share of the cost of multilateral programs for the acquisition and construction of military facilities and installations (including international military headquarters) and for related expenses for the collective defense of the North Atlantic Treaty Area.
(b) Funds may not be obligated or expended in connection with the North Atlantic Treaty Organization Security Investment program in any year unless such funds have been authorized by law for such program.
(c)(1) The Secretary of Defense may make contributions in excess of the amount appropriated for contribution under subsection (a) if the amount of the contribution in excess of that amount does not exceed 200 percent of the amount specified by section 2805(a) of this title as the maximum amount for a minor military construction project.
(2) If the Secretary determines that the amount appropriated for contribution under subsection (a) in any fiscal year must be exceeded by more than the amount authorized under paragraph (1), the Secretary may make contributions in excess of such amount, but not in excess of 125 percent of the amount appropriated, only after the end of the 14-day period beginning on the date on which the Secretary submits, in an electronic medium pursuant to section 480 of this title, to the appropriate committees of Congress notice of the increase, including the reasons for the increase and the source of the funds to be used for the increase.