Then a reporter asked if America would hit back at Iran if it was behind it. Trump said: "Oh, they'll be hit very hard, don't worry."
That's everything we know.
Why this mattersSo let's back up. What actually happened on that flight?
Two days ago, a FlyDubai flight took off from the United Arab Emirates to Tel Aviv. 174 people on board. Most of them Israeli.
Mid-flight, the copilot stabbed the captain. The plane dropped out of the sky. Other people on board managed to land it in Tabuk, in Saudi Arabia.
The captain is Smit Machchhar, an Indian national. He's in stable condition.
The copilot is an Omani national. He's under arrest right now. Saudi Arabia, Israel, the UAE, America and Oman are all working together to figure out why he did it.
A regional official briefed on the investigation put it plainly: all scenarios, from terrorism to mental disorders, are being looked into, and nothing is ruled out for now.
So nobody official has said Iran did this. Not Saudi Arabia. Not the UAE. Not Oman. Not India.
Netanyahu has said the suspect went through what he calls Islamist indoctrination. He didn't give details. And he didn't name Iran.
Here's the part that matters. A day ago, Trump said he was mostly relying on information from Netanyahu, and he wasn't even sure if it was accurate.
Today, he's telling reporters the answer is "yes".
And on that same day, Netanyahu is the one saying it's too early to tell.
So the two leaders aren't lined up here at all.
Now, the bigger picture. America is already building up its forces in the region. Around 9,000 troops are heading there by ship right now.
That includes the USS Theodore Roosevelt carrier strike group and the USS Makin Island amphibious group. More than 7,000 sailors. Over 2,000 Marines.
A US official says this could put three American carriers in the region by the end of October.
Trump has also said something else, in a Time magazine interview published today. He said it's possible he ramps up bombing in Iran after the 3 November elections.
He also said he turned down Iran's latest ceasefire offer, even though it included opening the Strait of Hormuz. He called it not good enough.
America and Iran have been at war since February. Iran hasn't responded to any of this yet.
So here's the real question. Is Trump's threat built on actual evidence? Or is it the same shaky information he said, a day ago, he couldn't even vouch for?