President Donald Trump warned on Thursday that Iran would face severe American retaliation if investigators determine that Tehran had any role in the attempted downing of a FlyDubai passenger flight, an extraordinary midair attack that investigators say was carried out by the plane's own copilot. FlyDubai Flight FZ1073 was traveling from Dubai to Tel Aviv on Wednesday when the copilot assaulted the captain in the cockpit and tried to crash the Boeing 737 MAX 8, according to preliminary findings from Saudi authorities. The aircraft plunged before passengers and other crew members intervened, restrained the attacker, and helped regain control of the plane. It made an emergency landing in Tabuk, in northwestern Saudi Arabia, with around 180 passengers and crew members on board. Everyone survived. Both pilots were injured in the assault and received medical treatment in Saudi Arabia before being cleared to continue on to Abu Dhabi on Thursday, according to Saudi and airline officials. A passenger who helped subdue the copilot, identified as Yaniv Hayun, said the man repeatedly shouted "Kill me" after being restrained, which Hayun interpreted as a sign that the attacker believed his plan had failed. Asked by reporters at the White House on Thursday whether he had been briefed on any link between the attack and Iran, Trump said the investigation was still underway. "I would say the answer, based on what I'm hearing, is yes, but we're working on it right now," he said. He offered no evidence to support his suspicion. Pressed on whether the United States would retaliate against Tehran if a connection were established, Trump was blunt. "Oh they'll be hit, very hard, don't worry," he said. "You just ask them," he added. "They know what happened. They'll be hit very hard." The president's remarks went well beyond what investigators have said publicly. Israeli Prime Minister Benjamin Netanyahu said on Thursday that it was too early to determine whether Iran played any role in the attack, and two Israeli security officials told Reuters that investigators had so far found no Iranian connection. Israeli, Emirati, and Saudi authorities are jointly examining the motive, and the possibility that the copilot acted alone remains under investigation. Netanyahu said investigators had learned that the Omani copilot had undergone "Islamist radical indoctrination." An Israeli official said the suspect's social media activity included references to killing Jews, and Netanyahu said the man appeared to have been suicidal. Israeli Defense Minister Israel Katz described the incident as an attempted terrorist attack. FlyDubai said its crew secured the aircraft and landed it safely. Trump's warning came against the backdrop of a war now in its seventh month. The United States and Israel launched Operation Epic Fury against Iran on February 28, and Iran continues to control the strategic Strait of Hormuz more than seven months after the initial strikes. Diplomatic efforts to end the fighting appear to have stalled: Trump publicly rejected Tehran's latest proposal to end the war just days ago, and Iranian officials said Wednesday they had received an official American response to that proposal without saying what it contained. In a Time magazine interview published Thursday, Trump signaled a harder line. He said he would not accept proposals from Iran that he "wouldn't have approved a year ago" and left open the possibility of resuming American bombing after the Nov. 3 midterm elections. He also repeated the threat he made in his speech to the United Nations General Assembly last week to "annihilate" Iran. The Wall Street Journal reported that the United States is expected to deploy a third aircraft carrier and as many as 10,000 additional troops to the Middle East by the end of November, keeping military pressure on Tehran while the investigation continues. The threat also comes as Republicans face mounting political pressure ahead of the Nov. 3 midterm elections, with Trump's approval ratings near record lows amid the Iran war and a surge in the cost of living tied to high oil prices. How the administration handles the FlyDubai investigation — and whether it acts on the president's warning — could shape the final weeks of the campaign.