The problem with using nuclear bombs to gank the Soviets is production. The Americans more or less used their entire nuclear arsenal on Japan, with a single bomb ready in the reserves. At most. And that's after several months of Uranium refinement. Admittedly I have no idea how many bombs were still under construction when WWII ended, or the projected rates of production assuming that WWII continued against the Soviets, but I think it's a safe bet that the Allies wouldn't have been wiping out the Russians with nuclear hellfires anytime soon. But on the other hand, strategic deployment of nuclear bombs to eliminate Russian production centers should tip the advantage towards the Allies. So... sucks to be the Russians?
In 1945, six warheads were available by the end of the year. 1946, that goes up to 11, then 32 in 1947, and by the end of 1948, it skyrockets to 110
[Ref], most of which were Mark 3 "Fat Men" implosion weapons. In other words, that's Moscow, Stalingrad, Leningrad, Vladivostok, Sevastopol, and oh, let's say Baku hammered in an instant. That said, it's not the end of the world. These were the little suckers used on Nagasaki, not what we of the 21st century usually think of when we hear "nuke". The first proper post-war bomb, the Mark 4 (a comprehensive rationalization and simplification of the Mark 3), didn't enter production until 1949, and the first major expansion of explosive yield wouldn't come until the 1952 Mark 5. You can expect a massive expansion in the Mark 4 program under ongoing wartime pressures, but I'd expect that to actually take resources from the Mark 5 and Snark (the first American ICBM) projects as well.
The real threat to the Soviets in the near term would be a massive step-up of a conventional bombing program, not the nuclear arsenal - in other words, the part of the aerial campaign that contributed to bringing Germany and Japan to their knees. The Soviets in 1945 are at the very end of their logistics tether, and this is not helped by the fact that their logistics are in large part hugely reliant on Allied Lend-Lease shipments of trucks. A war with the Soviets will stretch from Berlin to Iran (which at this point is still effectively partitioned between the Soviets and Britain due to Operation Countenance) to China and Korea. Bombers operating out of the Middle East can immediately strike at Soviet oil refineries at Baku, and other trans-Ural industries are also at risk. The issue is actually if the Allied powers can actually finish the job. Their logistics aren't that much better, and they also have to deal with domestic issues as well. The war was supposed to be over by this point; continuing it by backstabbing a fellow ally is not going to be a pleasant task, nor a popular one. They'll have to fight all the way from Germany to the Urals against not the disorganized and micromanaged-to-oblivion Red Army of 1941, but the hardened and experienced fighting force that is the Red Army of 1945.