With the approval of the President, the Secretary of the Treasury may borrow on the credit of the United States Government amounts necessary for expenditures authorized by law and may issue bonds of the Government for the amounts borrowed and may buy, redeem, and make refunds under section 3111 of this title. The Secretary may issue bonds authorized by this section to the public and to Government accounts at any annual interest rate and prescribe conditions under section 3121 of this title.