President Donald Trump has expressed his anger at a lack of help from Nato countries cooperating with the US to reopen the Strait of Hormuz, a narrow waterway through which more than 20 percent of the world's crude oil is normally transported.
On Monday, he announced that "numerous countries have told me they're on the way", without naming any publicly.
"Some are very enthusiastic about it, and some countries that we've helped for many, many years, we've protected them from horrible outside sources, and they weren't that enthusiastic. And the level of enthusiasm matters to me," he said.
Experts have warned that escorting tankers or undertaking any mission in the strait would be a "very dangerous mission".
European leaders in particular have made it clear they do not want to risk moves that would drag them into the wider war with Iran - particularly as they view the US-Israeli attacks on the Islamic Republic as illegal and without a United Nations mandate in the first place.
