President Donald Trump yesterday announced an initiative to guide stranded commercial ships through the Strait of Hormuz, prompting the Iranian regime to threaten to attack any vessel that attempts to pass through the waterway without its permission.

Trump said the initiative would begin today and that interference by the regime’s Islamic Revolutionary Guard Corps (IRGC) would be dealt with “forcefully.”

He did not provide details.

The US military said it would coordinate safe passage by stranded ships.  It did not say it would escort them but said warships and jetfighters would provide support.

The Iranian regime said any US Navy ship approaching or entering the Strait would be “attacked.”

The US military denied a regime claim today that it had struck an American naval vessel with two missiles, saying no such attacks had been attempted.

The United Arab Emirates today accused the IRGC of staging a drone attack on a tanker of its state oil company trying transit the Strait.  There was no information about casualties or damage.

A ceasefire between the US and Iran has been in place since 8 April, and neither has an interest in returning to full-scale war.

With negotiations for ending the conflict at an impasse, dueling blockades are looming large.

The regime since the war began on 28 February has been choking the Strait of Hormuz, the narrow waterway at the mouth of the Gulf through which 20 percent of global oil supplies pass in normal times.

In response, the US Navy since 13 April effectively has blockaded Iran by tracking ships that make port calls and intercepting them outside the Gulf.

The gambit Trump announced yesterday clearly was aimed at undercutting Iran’s effective control over the Strait.

But it could lead an exchange of fire that could spark wider hostilities, including renewed US airstrikes on Iran and IRGC missile and drone attacks on the Gulf Arab countries and Israel.

Short of that scenario, the test of wills between Trump and the Iranian regime will continue.

Iran faces an economic catastrophe if it cannot resume oil exports in the near future.  But its rulers are religious fanatics engaged in an existential war against their chief ideological foe, meaning they have an enormous capacity to absorb pain.

Trump, who is sensitive to elevated gasoline prices and market volatility in the US, has more practical concerns.

The Gulf Arab countries routinely are arresting people, including Westerners, who share cell phone videos of or social media posts about local military assets and Iranian missile and drone impacts. 

Israel and the Lebanese government on 23 April extended their ceasefire agreement for three weeks, keeping in place the lull in fighting between Israeli forces and the Lebanese Shia militia Hizbollah, an Iranian proxy.

That fighting has ticked up in the past 10 days although Israel has not resumed bombing Beirut.  

Full-scale hostilities between Israel and Hizbollah almost certainly would re-erupt if the US-Iran ceasefire collapses.