They have no money
They have nothing to sell to get money
They cannot get a loan
Their currency is hyperinflating and people spent all they had just to get rid of it. Including on food that could be stored. Now there is no storable food (or much else) in their grocery stores.
. . . and now the news has surfaced, their strategic food reserves are empty. It may have been fed to the army (which is losing its fight) or it may have been stolen, but it is gone. This is a problem. This is how you begin to have terms dictated to you by your military enemies. Ukraine may be lucky to get out of this with their west intact as a nation and the rest subdivided.