"Nothing is going through" the Strait of Hormuz, shipping insider says

London — The U.S. military's Central Command repeated an assertion on Tuesday evening that has been made by the Trump administration many times over the last two weeks, insisting that "despite Iranian aggression, the Strait of Hormuz remains open for commercial vessel traffic."

CENTCOM acknowledged in the same statement that Iran had launched more than 30 attacks on commercial vessels since the war began, which it said had "endangered hundreds of innocent mariners and undermined freedom of navigation."

President Trump, who has himself declared the strait open many times recently, threatened on Wednesday to destroy an Iranian bridge or power plant for every new attack targeting a ship in the vital waterway.

Despite the U.S. president and military continuing to urge vessels to use a southern route through the strait, in defiance of Iran's threats, few shippers seem willing to risk it.

The Joint Maritime Information Center in Bahrain, a military partnership that includes the U.S., said commercial traffic in the Strait of Hormuz fell to a three-week low on Tuesday amid ongoing Iranian attacks. CBS News tracked just three commercial ships — two cargo vessels and the Chinese-owned tanker Hsin Ocean — transiting the strait on Tuesday.

Between July 13 and 19, only two ships transited the strait using the U.S.-backed southern route that hugs the coast of Oman. Both transits were dark, meaning the vessels had turned off their AIS broadcast systems, according to a Lloyd's List analysis.

Last week, Dimitris Maniatis, CEO of the Greek maritime risk management company Marisks, said ship crews were unwilling to make the trip through the strait following the breakdown of the U.S.-Iran ceasefire that held for less than three weeks.

"There's nothing physically obstructing the navigation of any vessel willing to transit the strait, and there are vessels that trade locally and are entirely unaffected by everything that's going on, however, if we're talking about large ocean-going, internationally owned-and-operated merchant vessels, nothing is going through," Maniatis told CBS News on Wednesday.

U.S. support for ships that choose to risk Iranian attacks by taking the Oman route is limited to air support as they attempt the transit as part of a convoy, Maniatis said, "and this is definitely not enough, because we see that, despite the best efforts and intentions of the U.S. Navy, vessels continue to be hit while they're crossing the southern corridor."

Greek shipping giant Dynacom was one of the last international operators willing to send crews through the strait,