LIVE: Trump threatens to decimate Iran in 4 hours; deadline ends 6.30 am IST tomorrow

US President Donald Trump has lashed out at the North Atlantic Treaty Organisation (NATO), accusing the alliance and other friendly nations such as South Korea, Japan and Australia of failing to help the US in the Iran war.

Trump's remarks at a press conference at the White House on Monday came days ahead of NATO Secretary General Mark Rutte's visit to Washington to meet the US President, who has dismissed the alliance as a "paper tiger".

Trump said the war with Iran had left a mark on NATO "that will never disappear in my mind." The US President made it clear that the differences with NATO began when it spurned his move to take Greenland.

"NATO is a paper tiger that (Russian President Vladimir) Putin's not afraid of," Trump told reporters here.

On the Iran war, Trump said NATO members actually "went out of their way not to help".

"Look, we went to NATO. I didn't ask very strongly, I just said, 'Hey, if you want to help, great'," the US President said.

"'No, no, no, we will not help,'" Trump said he was told, while not saying who he spoke to.

Trump said NATO members were now trying to engage with him and offer support only after the United States had already won the war. "They're coming to see me on Wednesday," he said, adding that "all of a sudden" they now wanted to send help.

"Japan didn't help us, Australia didn't help us, South Korea didn't help us, and then you get to NATO - NATO didn't help us," Trump said.

"We've got 50,000 soldiers in Japan to protect them from North Korea; we have 45,000 soldiers in South Korea to protect us from Kim Jong Un," Trump said.

Trump said he gets along "very well" with North Korean leader Kim Jong Un.

"You know who else didn't help us? South Korea didn't help us. You know who else didn't help us? Australia didn't help us. You know who else didn't help us? Japan," Trump said.

"But we have 45,000 people, soldiers in harm's way, right next to Kim Jong-un with a lot of nuclear weapons—45,000—what should have never happened," he said.

"If a certain president, I'm not going to mention this president, I happen to like him, believe it or not, but if a certain president did his job, Kim Jong-un would not have nuclear weapons, but they're all afraid to do their job properly," Trump said.

He also suggested that the widening rift between the United States and NATO began earlier, when he first proposed taking over Greenland.

"It all began with, if you want to know the truth, Greenland," Trump said.

"We want Greenland. They don't want to give it to us. And I said, 'bye, bye'," the US President said.

Ayatollah Mojtaba Khamenei expressed condolences over the killing of the Revolutionary Guard's intelligence chief.

In a written social media post, Khamenei said Maj Gen Majid Khademi joined a “steadfast line of warriors and fighters” to sacrifice their lives. Israeli strikes have killed dozens of top Iranian leaders, including Khamenei's father.

The younger Khamenei has not been seen or spoken in public since he succeeded his father as supreme leader.

Trump threatened to jail the journalist who first reported that US forces were searching for an F-15 weapons officer shot down in Iran, if they don't reveal their sources.

“The person that did the story will go to jail if he doesn't say, and that doesn't last long,” Trump said.

Trump didn't name the journalist or news organisation. He said the leak tipped off the Iranians, endangering the officer and his rescuers. He called the leaker “a sick person”.

Speaking at a White House press conference, CIA Director John Ratcliffe said the agency used “exquisite technologies that no other intelligence service” possesses to locate the aviator after the F-15 was shot down in Iran.

At the same time, the CIA mounted a deception operation to mislead the Iranians who were looking.

Ratcliffe said the search and rescue operation was “comparable to hunting for a single grain of sand in the middle of a desert”.

The CIA declined to respond to questions Monday about the kind of technology used to locate the airman.

A US aircraft that crashed amid the search for the downed airmen was hit by enemy fire while engaging Iranian forces, Gen Dan Caine, the chairman of the Joint Chiefs of Staff, said Monday.

Caine, speaking at a briefing at the White House, said that a US A-10 Thunderbolt aircraft was “violently suppressing and engaging the enemy in a close-in gun fight to keep them away” from the pilot of a downed F-15 fighter jet while also being “primarily responsible for communicating with the downed pilot”.

Caine said that after being hit, “this pilot continued to fight, continued the mission, and then upon exit, flew his aircraft into another country and determined that the airplane was not landable.” The pilot then decided to eject over friendly territory and, according to Caine, “was quickly and safely recovered, and is doing fine.”

“Not everybody was on board,” Trump said about the rescue mission of the US airman from the downed jet. “There were military people that said, You just don't do this.'” Referring to Hegseth and Caine, Trump made sure to clarify: “These two were totally on board.”

Asked why Iranians would want him to follow up on his threat to blow up the country's infrastructure, Trump says everyday citizens are “willing to suffer ... in order to have freedom.” “Please keep bombing. Do it,'” Trump claimed US officials have heard Iranians say via “intercepts”.

“And these are people that are living where the bombs are exploding,” he said.

He added, “And when we leave and we're not hitting those areas, they're saying, Please come back, come back, come back.'”

Trump said the F-15E fighter jet that set off a two-day search-and-rescue operation was downed by a shoulder-launched rocket.

Trump described the weapon as a “hand-held shoulder missile — heat-seeking missile”.

The president went on to suggest that the fighter jet was ultimately downed not by the explosion but because of related damage to the aircraft's engines.

“They shot it and it got sucked in right by the engine,” Trump said.

The Israeli and Greek defence ministries signed the four-year export agreement Monday in Athens, said a statement from Israel's defence ministry.

The system, called PULS (Precise & Universal Launching System), is built to launch rockets of different ranges, the statement said.

Israeli defence giant Elbit Systems will supply the rocket launchers and the warheads to Greece. Greek defence industries are expected to produce some parts of the system.

UN Secretary-General Antonio Guterres warned the US that attacking civilian infrastructure is banned under international law, his spokesman said Monday.

“Even if specific civilian infrastructure were to qualify as a military objective,” spokesman Stephane Dujarric said, an attack would still be prohibited if it risks “excessive incidental civilian harm.” A court would need to decide whether such attacks were war crimes, he said.