Did the US exercise a formal right to withdraw from JCPOA as set out in the treaty itself?

Question

It's been said in a comment here on another equestion

Trump "withdrew" from JCPOA because he formally indeed did so. Iran "violates" JCPO because it did not formally withdraw from it, so is in fact violating it. Simple.

But is it that simple? According to Vox:

Trump’s Iran deal announcement was made in a Tuesday afternoon White House address, in which he announced that he would reimpose sanctions on Iran’s oil sector that had been lifted as part of the agreement. This put the US in violation of its obligations under the agreement, and thus constitutes a unilateral American withdrawal from the deal.

(Emphasis mine.)

As an example of a different US behavior, Trump didn't simply and abruptly "withdraw" from the Paris agreement, but followed a procedure set out in the treaty itself, although he did announce his intention to do so well in advance.

Did the US invoke a specific clause in JCPOA that allows them to "withdraw"? If not, is there some general compact in international law (e.g. the Vienna Convention on the Law of Treaties) that one state can withdraw in anyway they like from a treaty, unless the treaty says otherwise?

Answer 1

No. The JCPOA is not a treaty, or even an executive agreement, as viewed by US Law. It is merely a non-binding political agreement. It was never put before the Senate to "Advise and Consent," and thus was never challenged to the 60 vote threshhold.

Instead, there was a measure of political cowardice in the passage of the Iran Nuclear Agreement Review Act, that subverted the Constitution by requiring votes for either Approval or Rejection, with the President having veto power of either.

Since JCPOA was a non-binding political agreement between the Obama Administration, the rest of the P5+1, and Iran, US involvement was only guaranteed for the remainder of the Obama Administration.

This is an expression of the narrow powers distributed among the branches of the Federal Government, and one of the checks placed on the Executive from the Legislature. The President doesn't have the authority to enter into binding agreements unilaterally; Congressional endorsement is required.