In order to help the Allies, FDR had to...?

Pledge not to get militarily involved. Not really a cash-and-carry policy; it was more commonly known as lend-lease, where equipment and goods were supplied directly to the Allies on the understanding that repayments would be made after the war. America was, however, forced into the war after the Japanese attack on Pearl Harbour; and lend-lease left Great Britain greatly in debt to the USA after the end of the war.