Most other nations would not have been involved. The reason for the sale to United States by Russia was specifically to weaken Britain. Remember this is at a time when Russia was at odds with Britain. They had recently fought in the Crimea War against each other, they also had conflicting interest in Asia. Russia had also fought against France, Sardinia and the Turks in the Crimean war, so most other major powers they were not on good terms with. That would leave Prussia, Spain, and Austria for powers, but none of them really had the capabilities to take over and manage such a large far away territory.