The preliminary deal to end the war between the United States and Iran seeks to quickly reopen the Strait of Hormuz, but companies said on Monday that they need more details before resuming full navigation.
Since late February, when the United States and Israel attacked Iran, the strait has been effectively closed, leaving hundreds of ships stranded in the Persian Gulf, unable to transport oil and gas to global markets.
“There are a lot of questions that need to be clarified,” said S.V. Anchan, the chairman of Safesea Group, a shipping company based in Piscataway, N.J., that has two ships in the gulf, both of which had been attacked since the war’s start. One of the ships was so badly damaged that it was not operating and the other was waiting to leave the gulf.
Mr. Anchan said he wanted a clear commitment from Iran that ships could pass through the strait safely. “We want to hear from the Iranians that they will not attack us,” he said.
Another shipping executive, Andreas Enger, chief executive of the Norwegian shipping company Höegh Autoliners, said that news of the agreement was not enough to allow for the immediate resumption of ships through the strait.
“But let’s hope that it is the start of the process that will get us there,” he said.
Mr. Enger said it could take weeks or even months for him to feel comfortable sending ships into the Persian Gulf. “There very well may still be uncertainties and unresolved issues that would drag this out even longer,” he said.
The Japanese Shipowners’ Association said that it would wait for “more concrete information,” according to a local media report. There are 38 Japanese-related vessels stranded in the gulf, the association said.
The United States and Iran were expected to sign the agreement on Friday in Geneva. Critical issues that have divided the countries, including the fate of Iran’s nuclear program, have been deferred to later negotiations. The text of the agreement, which Iranian officials described as a memorandum of understanding, has not been released.
President Trump said on Sunday that the agreement with Iran would ultimately ensure that the Strait of Hormuz was “permanently toll-free.” As of Monday, Iranian officials had not commented on the specifics of the agreement.
In retaliation for the U.S.-Israeli strikes, Iran has asserted a role of gatekeeper of the strait, attacking vessels to deter ships. This campaign pushed up oil prices and gave Iran valuable leverage against the United States. Some ships were able to get out of the gulf through the strait. They did so with Iranian permission or with assistance from the U.S. military. Kpler, a ship tracking company, said about 500 large commercial vessels remained in the gulf.
Arsenio Dominguez, the head of the International Maritime Organization, said on Monday that the agreement was “an important step toward restoring safety in this vital maritime corridor for seafarers and ships.”
But he added that it would take time to ensure that security guarantees were put in place to evacuate the roughly 11,000 stranded seafarers.
There are also significant logistical steps that need to be taken for ships to begin to safely pass through the strait.
Shipping companies would want a neutral body, like the International Maritime Organization, to identify safe routes and a sequence for ships to exit, said Jakob P. Larsen, the chief security officer at Bimco, the world’s largest shipping association.
“If they all go in one big pile, there’s a really big risk of navigational incidents, collisions, things like that,” he said.
In recent weeks, a small number of ships have entered the Persian Gulf. A test of any final agreement would be the willingness of companies to resume traffic into the gulf in large numbers.
“We would need clear assurances from both sides that the strait is fully open and safe,” Mr. Larsen said. “It’s not enough that transits are permitted. They also need to be safe.”
Hisako Ueno contributed reporting from Tokyo.
