>>6801311(lb)
Let's be clear: It was, as you say, an "agreement" but it was not a treaty (it would not have passed the Senate). What one President (illegally) "agrees" to, another can "disagree" to.
I remember that Ayatollah Khomeini was exiled in France, then returned triumphant at the overthrow of the Shah. Was always curious why he was being sheltered; later turned to suspicion he was some DS agent. Don't know how to dig on this idea. Whole thing was pre-internet.
As was the oil tanker attack, imo. Japanese PM Abe in Iran trying to be the go-between for Iran and US; and we're supposed to believe that Iran would be stupid enough to attack a Japanese oil tanker? Puh-LEEEZE!
Wasn't commenting on the rightness or wrongness of anything Trump might be doing to "bypass" Congress. Merely noting that Trump's dis-agreement from Obama's agreement was itself totally legit, in refutation to your point.