This is coolbert:
LL = Lend-Lease.
MORE on the warship or cargo vessel carrying cargo of immense value, sunk by hostile military action, recovery of treasure on occasion successful.
Thank here serendipity and the answer from Quora:
"Did the Soviets repay the USA after the Lend-Lease policy ended?"
ALL OF THIS A RESULT OF REVERSE LEND-LEASE AS IT IS TERMED?
"During the war the USSR provided an unknown number of shipments of rare minerals to the US Treasury as a form of cashless repayment of Lend-Lease. This was agreed upon before the signing of the first protocol on 1 October 1941 and extension of credit. Some of these shipments were intercepted by the Germans. In May 1942, the HMS Edinburgh was sunk while carrying 4.5 tonnes of Soviet gold intended for the U.S. Treasury. This gold was salvaged in 1981 and 1986. In June 1942, the SS Port Nicholson was sunk en route from Halifax, Canada to New York, allegedly with Soviet platinum, gold, and industrial diamonds aboard. However, none of this cargo has been salvaged, and no documentation of it has been produced."
Read of the gold salvage expedition to the Edinburgh, successful.
Read of the rediscovery of the Nicholson. Items of great value not recovered.
THESE SHIPMENTS WERE AN INSTANCE OF R PRECIOUS METALS ESSENTIAL FOR THE WAR EFFORT?
See here also recent previous blog entry with a similar topic and additional links.