family housing functions of the Department of Defense (other than the military departments), as specified in the funding table in section 4601. (b) Limitation on total cost of construction projects Notwithstanding the cost variations authorized by section 2853 of title 10, United States Code, and any other cost variation authorized by law, the total cost of all projects carried out under section 2401 of this Act may not exceed the total amount authorized to be appropriated under subsection (a), as specified in the funding table in section 4601. XXV International programs A North Atlantic Treaty Organization Security Investment Program 2501. Authorized NATO construction and land acquisition projects The Secretary of Defense may make contributions for the North Atlantic Treaty Organization Security Investment Program as provided in section 2806 of title 10, United States Code, in an amount not to exceed the sum of the amount authorized to be appropriated for this purpose in section 2502 and the amount collected from the North Atlantic Treaty Organization as a result of construction previously financed by the United States. 2502. Authorization of appropriations, NATO (a) Authorization Funds are hereby authorized to be appropriated for fiscal years beginning after September 30, 2019, for contributions by the Secretary of Defense under section 2806 of title 10, United States Code, for the share of the United States of the cost of projects for the North Atlantic Treaty Organization Security Investment Program authorized by section 2501 as specified in the funding table in section 4601. (b) Authority to recognize NATO authorization amounts as budgetary resources for project execution When the United States is designated as the Host Nation for the purposes of executing a project under the NATO Security Investment Program (NSIP), the Department of Defense construction agent may recognize the NATO project authorization amounts as budgetary resources to incur obligations for the purposes of executing the NSIP project. B