As you said, The US withdrew from the JCPOA in first place NOT Iran. Regardless of the noise and the suggestion that the USA is running out of patience, what can it do? This is an article in a serious US forces mag which was published following Iran's successful attack on the Al-Assad airbase in Iraq. If you go half-way down the article there is a map showing the range of Iran's missiles. Not only are many US bases within range but also Israel's nuclear facility near Dimona, so despite the noise it is very unlikely any military action will be taken. https://www.defensenews.com/opinion/commentary/2020/01/13/iran-attack-highlights-us-missile-defense-vulnerability