White House seems to have failed to anticipate that Tehran would fight back by trying to impose costs on the west

Middle East crisis – live updates

If there was a moment when the absence of a US strategy on Iran was exposed, then this was it. Donald Trump demanded on Saturday that the UK, China, France, Japan and others participate in a naval escort for oil tankers through the strait of Hormuz.

Despite launching the attack on Iran, with Israel, the White House does not seem to have fully anticipated what was likely to follow. Iran had few good military options for fighting back, but attacking US bases, US allies and merchant shipping in the Gulf was the most obvious response – to try to impose costs on the west.

Iran had been gearing up for a long period of resistance, with Ali Khamenei, the former supreme leader, pressing subordinates to name four levels of succession in the expectation that he and others might be killed.