A senior general has said the US wants to create an international military coalition to safeguard waters around Iran and Yemen.
Marine General Joseph Dunford said he wanted to "ensure freedom of navigation" in the region, which provides essential trade routes.
Last month the US blamed Iranian-backed fighters for attacks on two tankers.
Gen Dunford said the US was in talks with a number of countries who had the "political will" to support the plans.
The US would provide "command and control" ships, he said, but the aim would be for other countries to offer boats to establish patrol between those ships.
Gen Dunford said the US would "work directly with the militaries to identify the specific capabilities" each country has to support the initiative.
The Straits of Hormuz and the Bab al-Mandab are essential strategic marine locations, providing access from the ocean into the Gulf and the Red Sea.
The general said the size of the initiative depended on the number of countries which decided to take part.
"With a small number of contributors, we can have a small mission," he said. "We'll expand that as the number of nations that are willing to participate identify themselves."
Everyday, nearly four million barrels of oil pass through the Bab-al Mandab to the rest of the world.
Why is the US so concerned about shipping?
The US accused Iran of attacking two oil tankers with mines in June, just outside the Strait of Hormuz - an accusation denied by Iran.
Days later, an unmanned US drone was shot down by Iranian forces in the Gulf.
Iran said it had violated Iranian airspace and would send a "clear message to America". The US insisted the drone had been over international waters. President Donald Trump tweeted: "Iran made a very big mistake!"