There is authorized to be appropriated to the President to carry out this part not to exceed $800,000,000, which may be made available until expended.
Upon agreement by the Government of Israel to provide to the Government of the United States funds equal to the difference between the amount required to complete the agreed construction work and the amount appropriated pursuant to subsection (a) of this section, and to make those funds available, in advance of the time when payments are due, in such amounts and at such times as may be required by the Government of the United States to meet those additional costs of construction, the President may incur obligations and enter into contracts to the extent necessary to complete the agreed construction work, except that this authority shall be effective only to such extent or in such amounts as are provided in advance in appropriation Acts.
Funds made available by the Government of Israel pursuant to subsection (b) of this section may be credited to the appropriation account established to carry out the purposes of this section for the payment of obligations incurred and for refund to the Government of Israel if they are unnecessary for that purpose, as determined by the President. Credits and the proceeds of guaranteed loans made available to the Government of Israel pursuant to the Arms Export Control Act [22 U.S.C. 2751 et seq.], as well as any other source of financing available to it, may be used by Israel to carry out its undertaking to provide such additional funds.