[flagged]
If the USA government had credible evidence that it is not so, they could have picked up the phone and presented their case to the other signatories. Or at least to their allies. Then once those countries were convinced that something is off they could have withdrawn together from the agreement. Would have less of a terrible optics than how it went down.
Not Just Obama.
Can the world be saved from central north American partisan squabbling please.
Re international agreements: yes, the idea is that _broad support_ is required for binding international agreements. Senate ratification represents broad support.
The JCPOA was written in pencil.