(a) The Secretary of Defense and the Secretary of each military department may make expenditures and contributions under section 18233 of this title without regard to section 3324(a) and (b) of title 31.

(b) Authority provided by law to place permanent or temporary improvements on land under section 18233 of this title may be exercised on land not owned by the United States—

(1) before title to the land on which the improvement is located (or is to be located) is approved under section 3111 of title 40; and

(2) even though the land will be held in other than a fee simple interest in a case in which the Secretary of the military department concerned determines that the interest to be acquired in the land is sufficient for the purposes of the project.