> Because every nuclear power developed their own enrichment processes and bomb technology, their bombs have different isotope ratios in the fallout. It's possi

> Because every nuclear power developed their own enrichment processes and bomb technology, their bombs have different isotope ratios in the fallout. It's possible to analyze the fallout to determine where the bomb came from. That might not tell you who is responsible (as the weapon may have been stolen), but it would at least tell you which country's nuke it was. A major plot point of Tom Clancy's A Sum of All Fears is exactly this. A bomb gets lost by the Israelis and acquired by terrorists (Arab nationalists in the book, neo-Nazis in the film) and detonated in Baltimore with the intention of starting a nuclear exchange between the US and the Soviet Union. It turns out the fissile material was made at Oak Ridge, crisis averted, tea^Wcoffee and medals in Washington.