Lazeelink,

You need to look up the Anglo-American Loan.  This loan was imposed by the United States on Britain for repayment (at 2% interest) of the monies, weaponry and second-hand ships the U.S. "lent" to Britain from 1939 to 1941, while the "America First" movement hampered FDR from actively engaging as an ally of Britain until Hitler declared war on the U.S. on December of 1941.  You need to read the terms of the Lend/Lease Act yourself.