United States President Donald Trump has told Japanese Prime Minister Sanae Takaichi he expects her country to “step up” to assist with securing the Strait of Hormuz amid the US- and Israeli-led war against Iran.

But at a news conference in the Oval Office on Thursday, a reporter pressed Trump about why he did not tell US allies like Japan in advance about his administration’s plans to attack Iran.

Trump responded with a quip about the Japanese sneak attack on the US naval base at Pearl Harbor during World War II.

“We wanted surprise. Who knows better about surprise than Japan, OK? Why didn’t you tell me about Pearl Harbor?” Trump asked Takaichi, who appeared uncomfortable.

“You believe in surprise, I think, much more so than us,” Trump added.

It was a remarkable moment in an otherwise short Oval Office media appearance for the two leaders, who are expected to discuss trade and global security.

Takaichi is among only a handful of leaders to visit the White House since the war against Iran began, and she is one of the first to meet with Trump after he pushed over the weekend for a coalition of allies to defend the Strait of Hormuz.

The strait is a vital artery for the oil trade, with nearly a fifth of the world’s supply passing through the narrow waterway. Iran, however, has largely shut down traffic through the strait, causing oil prices worldwide to spike.

In opening remarks, Takaichi condemned  ”Iran’s actions such as attacking the neighbouring region and also the effective closure of the Strait of Hormuz”.

But she also hinted at her concerns about the war overall, pointing to the “ severe security environment” it has created and its anticipated economic effects.

“The global economy is about to experience a huge hit because of this development,” Takaichi told reporters in the Oval Office, referring to the war. “But even against such backdrop, I firmly believe that it is only you, Donald, that can achieve peace across the world.”

The meeting between the two leaders comes as Trump continues to assert that Iran is on the verge of defeat, even as the continued closure of the Strait of Hormuz and Iranian strikes on energy infrastructure across the Middle East region throttle global energy markets.

“You could end this thing in two seconds if you wanted to,” Trump said of the war effort. “But we are being very judicious.”

Before the meeting with Trump, Japan and five European nations stated that they would consider “appropriate efforts” to help reopen the strait. It is unclear what such an effort might look like in practice.

Japan is further limited by its 1947 constitution, which the US imposed after World War II.

It establishes Japan as a pacifist country and includes a pledge that Japan will “renounce war” as well as the “threat or use of force”.

Still, Trump offered praise for Takaichi and signalled that he had promising conversations behind closed doors with Japan’s leadership.

“We’ve had tremendous support and relationship with Japan on everything,” Trump said. “nd I believe that based on statements that were given to us yesterday, the day before yesterday, having to do with Japan, they are really stepping up to the plate.”

Trump then quipped that Japan was offering help, “unlike NATO”.

Trump has given contradictory statements about the strait. In different public appearances, he has said that it is safe for ships to pass through and that the US could retake the strait alone.

“We don’t need much. We don’t need anything,” Trump said on Thursday. “We don’t need anything from Japan or from anyone else. But I think it’s appropriate that people step up.”

But Trump appeared to undermine his own statements over the weekend, when he told reporters he had reached out for assistance.

It “would be nice to have other countries police” the strait, Trump said aboard Air Force One. “We are demanding that these countries come in and protect their own territory. Because it is their territory. It’s a place from which they get their energy.”

In Thursday’s news conference, he emphasised that other countries, including Japan, received more of their oil and natural gas supplies by way of the strait than the US does.

He argued that it is therefore the responsibility of other countries to secure the strait.

“That country is close to demolished,” Trump said of Iran on Thursday. “The only thing is the straight. It’s very hard. You could take two people, and they could drop little bombs in the water, and they’re holding things up.”

Asian nations are expected to be among those hardest hit by surging energy prices, and Trump reasserted during the meeting that he had told Israeli Prime Minister Benjamin Netanyahu not to carry out more strikes on Iranian energy facilities.

An Israeli attack on the South Pars gasfield on Wednesday prompted retaliatory Iranian attacks against the Ras Laffan natural gas facility in Qatar, which accounts for about 20 percent of global liquid natural gas supply.

Asked if he would put US boots on the ground to secure the Strait of Hormuz, Trump responded that he had no plans to do so but would not tell the press if he did.