Iran's response options for Soleimani's death

The assassination of Qasem Soleimani has plunged Iran and the United States into their most serious confrontation since the hostage crisis in 1979.

President Donald Trump's decision to kill Soleimani removes one of the most obdurate and effective enemies of the US, and delivers a blow to the heart of the Islamic republic of Iran. It is also a dangerous escalation in a region that was already tense and full of violence.

The killing at Baghdad airport has increased tensions sharply, creating fears of a slide into an all-out war. That is no certainty. Neither the Americans nor the Iranians want one. But the crisis brought on by the killing of Soleimani - and a senior Iraqi ally - amplifies the chances of a bloody miscalculation.

Iran has sworn vengeance. That threat has to be taken seriously. Soleimani was at the core of the regime, and a talisman for Iran's hardliners. They will want to get even, perhaps more than that.