US Secretary of State Marco Rubio on Thursday warned that Iranian tolls on ships passing the Strait of Hormuz would spread to other waterways, risking "total chaos".
"International waterways do not belong to any nation state. This is a foundational principle in the world today, without which the world would be in total chaos," he told a Gulf Cooperation Council meeting in Bahrain.
"If in fact we accepted that you can charge money to use an international waterway because it happens to be near your territorial space, well then this will spread throughout the world like a contagion."
Rubio, on his first regional tour since the US and Iran signed a memorandum of understanding to end the Middle East war, said the US wants a peace deal but not "at any price".
"While we want a deal, we don't want a deal at any price," he said. "We want a deal that's good, we want a deal that's real, we want a deal that's verifiable, and we want a deal that's adhered to."
The top US diplomat, who has visited the heavily attacked UAE, Kuwait and Bahrain on his tour, also gave assurances that the interests of Gulf countries would be taken into account.
"We want to ensure... that there is no part of this deal that's undertaken that in any way undermines the security, the stability, or the prosperity of any of our partners in the Gulf region," he said.
Deal not 'at any price'
Marco Rubio also warned that a deal with Iran would not come at any price, as he sought to reassure Gulf allies that it would not undermine their security.
Rubio was in Bahrain as part of a regional tour of Gulf partners that were hit hardest by Iran during the Middle East war, which began on February 28 with a massive US-Israeli campaign of strikes against the Islamic republic.
The United States and Iran have signed a preliminary deal to end the war, embarking on negotiations expected to touch on thorny issues including Tehran's nuclear programme, sanctions relief and global energy flows through the Strait of Hormuz.
The Gulf and Israel have long voiced concerns about Iran's support for proxies in the region and its missile programme -- but it remains unclear whether these topics will be addressed in the negotiations.
"While we want a deal, we don't want a deal at any price," Rubio told a Gulf Cooperation Council meeting in Bahrain.
"We want to ensure... that there is no part of this deal that's undertaken that in any way undermines the security, the stability, or the prosperity of any of our partners in the Gulf region."
Tehran warns against unauthorized Hormuz
Iran's Revolutionary Guards on Thursday warned against any crossings of the Strait of Hormuz without authorisation, saying vessels not complying "will be dealt with".
The future of the strait, a vital route for energy shipments that was locked down by Iran during the war, is a key sticking point in negotiations between Tehran and Washington.
Tehran has said it plans to impose what it calls maritime service fees, as opposed to tolls, while the United States argues it is an international waterway and therefore should not be charged.
"The only authorised route for passage through the Strait of Hormuz is the route announced by the Islamic Republic of Iran," said the Revolutionary Guards, the ideological arm of Iran's military.
Any crossing without authorisation is "unacceptable and extremely dangerous", they warned in a statement.
They also denounced what they said was a new route through the waterway announced by "certain authorities", without elaborating.
Hormuz is a narrow stretch of water between Iran and the Gulf countries through which roughly 20 percent of the world's crude oil and liquified natural gas normally transits.
At its narrowest it is only about 30 kilometres (18 miles) wide.
The only route currently authorised by Iran runs through a corridor that follows the country's coast.
A memorandum of understanding signed last week by Tehran and Washington to end their war stipulates that commercial ships may transit the strait free of charge for the next 60 days.
With Iran and the US in negotiations, it is unclear what arrangements will be in place after that period.
Iran and Oman, which also borders the strait, announced on Tuesday that they would study the "costs" to be charged for services related to administration of the strait.
Oman says 'no transit fees' in Hormuz
Oman's top diplomat said no transit fees would be imposed in the Strait of Hormuz Thursday after Muscat and Tehran, which border the key waterway, had earlier said they were discussing service "costs".
Badr Albusaidi said "future arrangements regarding the Strait do not entail the imposition of any transit fees," during a meeting of Gulf foreign ministers in the Bahraini capital Manama with US Secretary Marco Rubio -- whose administration has repeatedly opposed any fees or tolls.
Iran slams NATO chief's comments
Tehran accused NATO on Thursday of "complicity" in the US-Israeli war against Iran, after the bloc's chief noted its support for the United States in the conflict.
Responding to US President Donald Trump's criticism of allies for not supporting the war, NATO boss Mark Rutte told Fox News that hundreds of American planes launched from bases in Italy.
Trump's second term has been marked by tensions with NATO allies, who have voiced skepticism over the need for the conflict in the Middle East.
"Country after country, ally after ally after ally, have made their bases available for Epic Fury," Rutte told US TV channel Fox News, referring to the US military operation in Iran.
"Five hundred US planes took off from US bases in Italy to support Epic Fury," he said, referring the US name for the operation against Iran.
Trump had told Rutte on Wednesday he was "let down" by members of the alliance who did not back his war against Iran.
Rutte also told Fox News that Romania "cut down on commercial air flights and airplanes because they had to use the airports for the tanker facilities" during the Iran war.
Iran's foreign ministry spokesman Esmaeil Baqaei condemned the NATO chief's admission of "active complicity" in the "unlawful war".
"This is a clear and damning admission of NATO's active complicity in an unlawful war of aggression against a sovereign UN Member State," Baqaei wrote on X.
He accused NATO of "a flagrant violation of peremptory norms of international law and the core principles of the UN Charter".
Italy was quick to distance itself from Rutte's words, which the defence ministry said gave "a completely misleading message by confusing the type of flights that were authorised".
It said Italy had allowed only "technical and logistical" US flights during Epic Fury under existing agreements with the United States.
Israeli soldier killed in south Lebanon
The Israeli military said Thursday that a soldier was killed the previous day in southern Lebanon, where clashes with Hezbollah militants have been reported despite a ceasefire.
Master Sergeant Basil Sweid, 32, a driver, "fell during operational activity", the military said.
A spokesman told AFP that he was killed when his vehicle overturned.
The military says 37 soldiers and one civilian contractor have been killed in southern Lebanon since fighting with Hezbollah erupted in early March.