Washington DC - It was billed as a press conference on the Iran war. But President Donald Trump seemed more interested in talking about gold decorations, before outing a lawmaker's terminal diagnosis.

Over the course of an hour, the former property magnate spent much of his time talking about the new ballroom he is building at the White House, and the renovation of a Washington arts center he has renamed after himself.

"You see the nice gold curtains?" Trump said after brief opening remarks on the Middle East war that has roiled the global economy and left 13 US service members dead, plus several thousand in the region.

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The drapes the 79-year-old president mentioned cover a window in the East Room of the White House that looks out onto the construction site for the $400 million ballroom.

"We have a magnificent ballroom being built... This whole floor will end up being a cocktail room for the ballroom before dinners," added Trump.

Monday's event was billed as a lunch for the board of the Kennedy Center, a panel which Trump handpicked to add loyalists as part of a crusade to rid what he views as left-wing influence from the storied Washington arts venue.

Trump then announced on his Truth Social network that he would be giving a "news conference" – only for the White House to make clear that he would be taking some questions from reporters, as he often does at such events.

Before questions, however, the oldest elected president in American history spoke for 40 minutes on pretty much any subject that came to mind.

The man who has built Trump-branded buildings in several cities appeared to be mainly interested in how he would decorate some of Washington's most prized real estate.

"It was painted a cheap gold, and we turned into a very expensively painted white, very heavy coat of very powerful white paint," Trump said of renovations that will keep the Kennedy Center closed for two years from July 4.

"We got rid of the gold columns, which looked always terrible. They look cheap, and they look fake – very much like the media."

Trump then turned to the Republican House Speaker Mike Johnson – but as Trump mused on the party's slim majority in the chamber, he gave what appeared to be private details about a congressman's poor health.

The president said he had called doctors on behalf of Representative Neil Dunn, adding, "he would be dead by June." The bespectacled Johnson then added: "Okay, that wasn't public."

Trump then added that "because I don't want to have a terrible story about this: I did it for him first. And for the vote second. But it was a close second, actually."

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Trump also paid tribute to his trusted chief of staff Susie Wiles, sitting on his left, whose breast cancer diagnosis he had revealed on social media a few minutes before the event.

By the time he got to questions, Trump didn't hold back either as he ripped into a series of world leaders over their apparent reluctance to help secure the Strait of Hormuz from Iranian attacks.

"Not perfect – but it's France," he said of President Emmanuel Macron's response. "Why do you have to meet with your team to find out whether or not you send some mine sweepers?" he added about British Prime Minister Keir Starmer.

Trump finished off with a glimpse into his foreign policy deliberations when a reporter asked about his reaction to an Israeli ground assault against Hezbollah in southern Lebanon.

"I was with the other night a person whose parents live in Lebanon," Trump said.

"I said, 'Really? How do you live in Lebanon?'... but they explained to me that it's really a different section of Lebanon. It's a section where Hezbollah is, and they get used to it, I guess."