As the US–Iran conflict entered its sixth day, fighting has widened beyond Gulf states and into Asia, convulsing global markets and prompting thousands of stranded tourists and residents to try to flee the Middle East.

Iran's foreign minister called the sinking of an Iranian warship off Sri Lanka on Wednesday, which killed at least 80 people, an "atrocity at sea".

He said the Iranian frigate IRIS Dena, a guest of the Indian navy with nearly 130 sailors on board, had been struck without warning in international waters, and warned that Washington would "bitterly regret" the precedent it had set.

"We have decided to fight Americans wherever they are," General Kioumars Heydari, a commander of the Islamic Revolutionary Guard Corps, told state TV, adding Iran did not care how long the war lasts.

Later on Thursday, the Revolutionary Guards said they had hit a US tanker in the northern part of the Gulf and the vessel was on fire. The Guards said in the statement carried by state media that in time of war passage through the Strait of Hormuz would be under the control of the Islamic Republic.

Türkiye said NATO air defenses destroyed an Iranian ballistic missile fired towards it on Wednesday, marking the first time the alliance member bordering Asia has been drawn into the Middle East conflict and raising the possibility of a major expansion involving its bloc allies.

But the Iranian Armed Forces General Staff on Thursday denied it had fired missiles at Türkiye, saying the Islamic Republic respected the sovereignty of "friendly" Türkiye, according to a statement carried by Iranian media.

In Washington late on Wednesday, Republican senators blocked a motion aimed at stopping the US air campaign against Iran and requiring that military action be authorized by Congress. That rejection leaves President Donald Trump's power to direct the war largely unbound, as the conflict continues to widen across the Middle East and beyond.

US Defense Secretary Pete Hegseth told his Israeli counterpart Israel Katz by telephone: "Keep going until the end – we're with you", according to a statement issued by Israel's defense ministry on Thursday.

Sri Lanka says trying to safeguard lives on second Iranian ship

Sri Lanka said it was trying to "safeguard lives" on a second Iranian ship off its coast on Thursday, a day after 87 people were killed in a US submarine strike on an Iranian warship in the same region, an attack that Iran said the US would "bitterly regret".

Sri Lanka's cabinet spokesman told parliament that Colombo was aware that there was another Iranian ship in Sri Lanka's exclusive economic zone outside its maritime boundary and it was "addressing the situation".

The cabinet spokesman was responding to questions from an opposition leader on whether the government was aware that another Iranian ship was near the port of Colombo.

"The President, defense officials, and all other relevant officials are aware and we are addressing the situation," spokesman Nalinda Jayatissa said. "We are doing our utmost to safeguard lives."

Jayatissa said that the IRIS Dena was sunk 19 nautical miles off Sri Lanka's southern port city of Galle and that two freezers had been dispatched from Colombo to store the 87 bodies recovered from the sea on Wednesday.

Iranian Foreign Minister Abbas Aragchi said the warship was struck in international waters without warning thousands of miles from the Gulf, where US and Israeli forces are striking Iran and Tehran is retaliating with missile and drone attacks.

"The US will bitterly regret the precedent it has set," Aragchi said in a post on X, adding that the warship was a guest of India's navy and was carrying almost 130 sailors.

Sri Lankan military rescuers responded to an early-morning distress call from the IRIS Dena on Wednesday and found 32 survivors. Search and rescue operations for an estimated 10 people who remain unaccounted for would continue on Thursday, authorities said.

The attack dramatically widens the scope of the war.

"An American submarine sank an Iranian warship that thought it was safe in international waters," US Defense Secretary Pete Hegseth said at the Pentagon. "Instead, it was sunk by a torpedo. Quiet death."

A Pentagon video purporting to have captured the attack showed the warship being hit by a huge explosion, which blew apart the rear of the vessel, lifting it from the water, and causing it to begin sinking from the stern.

IRIS Dena had taken part in a naval exercise organised by India in the Bay of Bengal from February 18 to 25 and was on its way back, according to the drill's website and Sri Lankan officials.

Azerbaijan says two people injured by Iranian drones 

Azerbaijan's foreign ministry lodged an official protest with the Iranian embassy on Thursday after a pair of Iranian drones flew across the border into Azerbaijan and injured two people at an airport in the Nakhchivan exclave.

"This attack on the territory of Azerbaijan contradicts the norms and principles of international law and contributes to increased tensions in the region," the foreign ministry said in a statement.

"We demand that the Islamic Republic of Iran clarify the matter in the shortest possible time, provide an explanation and take the necessary urgent measures to prevent such incidents from recurring in the future."

The statement said Azerbaijan reserved the right to carry out "appropriate response measures" against Tehran.

Azerbaijan's ministry said one drone fell on the terminal building of the Nakhchivan International Airport, which is approximately 10 kilometers across the border from Iran, and another drone landed close to a school building in a nearby village.

Video footage shared by the source showed black smoke rising near the airport and damage to the skylight inside the terminal building.

Gulf countries concerned about risk of Iran civil war, says EU's foreign chief

Countries in the Middle East have told European officials they are concerned about the risk of civil war in Iran as a result of the conflict between Tehran and the United States and Israel, EU foreign chief Kaja Kallas said on Thursday.

"When we talk to the countries in the region, they are also worried about civil wars inside ... the regime's leadership and what is going on there," she said ahead of a video conference with EU foreign ministers and representatives of the Gulf Cooperation Council on the situation in Iran and the broader Middle East.

She also said the EU is "extremely worried" about maritime security in the region and that it is trying to keep routes such as the strait of Hormuz open.

Russia accuses US and Israel of trying to drag Arab countries into a wider Middle East conflict

Russia on Thursday accused the United States and Israel of trying to drag Arab countries into a wider Middle East conflict by provoking Iran into striking targets across the region, and said there was no sign Washington and Tel Aviv would let up.

Arab states in the Gulf, all close US allies – some of which also have close ties with Russia – have come under Iranian drone and missile attacks since the United States and Israel launched their air strikes on Iran on Saturday.

Russian President Vladimir Putin spoke by phone to leaders of four Arab Gulf states on Monday, offering to use Moscow's ties to Iran to relay concerns about Tehran's strikes on oil infrastructure across the region.

Russia's Foreign Ministry in a statement on Thursday accused the US and Israel of deliberately trying to draw Arab Gulf states into a wider conflagration.