Just a brief further note on Lend Lease and why Stalin likely was beholden to
the US in the time frame of 1941 to at least the battle of Stalingrad in the
winter of 1942.
The timeline below fits in rather well with this notion that Harriman's proposal
had a deciding affect on Stalin in the matter of the release of the Polish Army
March 11, 1941 Lend Lease passed by Congress
October 1, 1941 US begins supplying USSR under a secret protocol
October 16, 1941 USSR government moved from Moscow to Kuibyshev
See also the following websites and the attachment on General Zhukov's opinion
on Lend Lease to see that in this grave situation Stalin was forced to bend to
subtle American pressure, such as and including Harriman's suggestion to move
Ander's army to Persia.