This looks like bad news. Iran's foreign minister, JMohammed avad Zarif, hass resigned. Apparently he has previously tried to resign several times, but President Rouhani refused to accept it. This time Zarif did it very publicly on Instagram, ah, the uses of social media. Anyway, apparently there is a chance he might still be talked into staying, but probably not. It seems that he has lost the favor of Supreme Leader Khamenei, and that effectively somebody lse is handling foreign policy now, almost certainly hardliners, perhaps from the Revolutionary Guards. The most obvious sign of this is that yesterday Syria's leader, Bashar al-Assad visited Tehran, and Zarif was not at the meeting with other top Iranian leaders. His reignation came later in the day after the meeting.
We do not know the details, but pretty clearly Zarif is out because of the US withdrawing from the JCPOA nuclear deal and imposing strong economic sanctions that have seriously impacted the Iranian economy, despite all other signatory nations have pledged to support the agreement and offset the sanctions. But the ability of the US to pressure compainies to withdraw from deaaling with Iran out of the threat of having no access to the US market, as well as pushing some nations to switch from importing oil from Iran, has had its impact. The upshot has been that all the hardliners in Iran who doubted the wisdom of negotiating the JCPOA that led to Iran giving up most of its potential nuclear weapons capability have come out to sneer and criticize the Rouhani government as a bunch of suckers. Foreign Minister Zarif was the point man in the negotiations, and so it appears that he is the scapegoat for now for all the trouble Iran is suffering as a result of Trump's actions.
In any case, anybodyin the US who thinks this is a good development is very fooliish.
Addendum: 2/27, 11:00 AM
This morning's Washington Post reports that President Rouhani is refusing to accept Zarif's resignarion. Not clear how all this will play out.