authorizes the President to appoint an official known as the "alien property custodian," who is responsible for "receiv[ing,] ... hold[ing], administer[ing], and account[ing] for" "all money and property in the United States due or belonging to an enemy, or ally of enemy The Act was originally enacted during World War I "to permit, under careful safeguards and restrictions, certain kinds of business to be carried on" among warring nations, and to "provid[e] for the care and administration of the property and property rights of enemies and their allies in this country pending the war