Some vessels are still moving through the Strait of Hormuz even as security fears in the region continue to grow, according to Rockford Weitz, a professor of maritime studies at Tufts University.

He said a limited number of operators willing to take the risk are already passing through the strategic waterway, and suggested others could soon follow. He also noted that Iran is still sending ships through the strait on routes bound for China.

Weitz said marine war-risk insurance could begin to return, although such cover would not shield ships from attack, and many shipping firms remain cautious, preferring to wait before resuming normal movements.

He added that some vessels crossing Hormuz have been switching off their transponders, underlining the level of danger involved. Naval escorts could help improve safety, though that kind of protection may still be several days away.