According to an Iranian state media report and an Instagram post under his name, Iranian foreign minister Javad Zarif resigned on Monday. What might have sparked the shock resignation?

Long identified as a key member of the more moderate faction in Iranian politics, Zarif was a key element behind the 2015 nuclear agreement. But with the Trump administration withdrawing from that accord and escalating its diplomatic and intelligence pressure on Iran in other areas, Zarif's credibility has diminished. Nor has Zarif's case been helped by the recently hardening European Union stance against Iranian activities on ballistic missile development and terrorist plotting.

This, it seems, left Ayatollah Khamenei deciding that Zarif was making the regime look weak without bringing any economic benefits. And while Zarif's resignation is a shock, it was notable that the foreign minister was excluded from a historic meeting between Syrian dictator Bashar Assad and Khamenei, and Iranian revolutionary guards chief Qassem Soleimani on Monday. Symbology of power is deeply important in Iranian revolutionary politics, and Zarif's absence signified his alienation from the supreme leader.

There is, however, an alternative explanation here. Because it's also possible that with the hardliner faction in Iran growing in anger and relative strength, Zarif may have also felt that his resignation would give President Rouhani, the erstwhile leader of the more moderate faction, new political space. Zarif may have believed that throwing himself on his sword, he would give the hardliners a sacrifice with which to sate their anger rather than pursue Rouhani.

Regardless, it's clear that the torments in Iranian politics are growing. And with them, the risk of regional conflict.