Seems the other nations are impotent eunuchs without US support. If the treaty was all that important to them, they should have been able to continue to enforce it. But, Russia and China don't seem to care if Iran has nukes, and the other players are total wimps.

Iran would have violated the deal in secret anyway. Why do you think they kept brewing nuclear fuel in those underground bunkers that Trump bombed. If they were on the up and up, all enrichment would have been done in plain sight.

Measures and treaties which seem solid at the time don't work in the long run.

The goal should be to prevent Iran (or anyone else) from ever having nukes, but that is impossible to assure with any treaty.

To avoid a nuclear holocaust, the powers with nukes have to refrain from using nukes in perpetuity. That ain't gon'na happen. It's only a matter of time until we encounter mass annihilation of the human species. Governments are not smart enough to exercise perpetual restraint.