In August, Saudi-led coalition forces used an American bomb to blow up a school bus in Yemen, reportedly killing at least 51 people, including 40 children.

What he's saying: In his first public comments on that attack, President Trump told "Axios on HBO" that the killings were "a horror show." But he declined to say if it's made him reassess American arms sales to the Saudis.

"I think it's a terrible situation. I hated seeing what happened with the bus and the children cause that's pure — that's a horror show when you see a thing like that, you saw the bus."

Why it matters: Yemen is the world's worst humanitarian crisis, according to the UN. The U.S. has been selling the Saudis weapons to fight the Iran-backed Houthis, and Trump has boasted repeatedly about the size of his Saudi arms deal.

"Axios on HBO" asked Trump whether it bothered him that the Saudi-led coalition has been using U.S. bombs to kill civilians.

"Bother's not strong enough," Trump replied. "That was basically people that didn’t know how to use the weapon, which is horrible."

Axios' Jim VandeHei then asked Trump if this gave him pause about selling American weapons to the Saudis.

"I don't want to see that," Trump replied. "That is a terrible thing. What's going on in Yemen generally is a terrible thing, and we're gonna see and we're looking at Yemen very carefully right now. We are actually studying Yemen very, very carefully."

I asked if Trump would handle the war differently if he were in the Saudis' place.

"I'll be talking about a lot of things with the Saudis," he continued, "but certainly I wouldn't be having people that don't know how to use the weapons shooting at buses with children."

What's next: Last week, the U.S. called for a cease-fire, but within two days, per the Washington Post, "the U.S.-backed Saudi-led coalition launched a fresh offensive."

The war has no end in sight. In a chilling piece, the New York Times Magazine's Robert Worth reported from the ground in Yemen that "Houthi officials say they have studied the Viet Cong’s tactics, and routinely refer to the war as the quagmire that will bring down the House of Saud."

In a chilling piece, the New York Times Magazine's Robert Worth reported from the ground in Yemen that "Houthi officials say they have studied the Viet Cong’s tactics, and routinely refer to the war as the quagmire that will bring down the House of Saud." The Houthis believe they have a mandate from God to continue their war, Worth's piece continues. They chant the slogan: "God is great, Death to America, Death to Israel, Curses on the Jews, Victory to Islam."

to continue their war, Worth's piece continues. They chant the slogan: "God is great, Death to America, Death to Israel, Curses on the Jews, Victory to Islam." The war has become a proxy fight between the Saudi-led coalition and Iran, and has put 14 million people at risk of starving to death.

For more on Trump's accounting for Yemen, watch our full interview with the President at 6:30 p.m. ET/PT on HBO.