“We were having negotiations with these lunatics, and it was my opinion that they were going to attack,” he said. Asked if Israel had forced his hand, as has been widely reported, he said, “If anything, I might have forced Israel’s hand.”

Global stock markets tumbled on Tuesday and the price of oil surged, as the widening conflict in the Middle East sent a shudder through the world economy and American and Israeli officials signaled that their bombing campaign against Iran could last weeks. At the White House, Mr. Trump predicted oil prices would fall once the fighting stopped; Mr. Merz said the high oil prices were damaging the world economy, an argument for ending the war quickly.

Asked who he would like to take over Iran, Mr. Trump gave a strikingly blunt answer. “Most of the people we had in mind are dead,” he said. “Now we have another group, they may be dead also, based on reports. So you have a third wave coming. Pretty soon we’re not going to know anybody.”

When asked about a worst-case scenario, he said: “I guess the worst case would be we do this and somebody takes over who’s as bad as the previous person. Right, that could happen? We don’t want that to happen. It would probably be the worst, you go through this and in five years you realize you put somebody in who’s no better.”

Fighting escalated on Tuesday between Israel and Iran-backed Hezbollah in southern Lebanon. The Israeli military said that it was carrying out additional strikes in Iran, and had targeted weapons storage facilities in Beirut, the Lebanese capital, as Hezbollah said it had fired attack drones at Israel. Israel’s advance in southern Lebanon prompted fears that it could be weighing a wider ground assault similar to the one it launched during its yearlong war with Hezbollah that ended in late 2024.

More than 800 people have been killed in the conflict across the Middle East since Saturday, when the United States and Israel launched their opening attacks on Iran and killed the country’s supreme leader, Ayatollah Ali Khamenei. The war has prompted a global market sell-off that intensified on Tuesday, with stocks and bonds slipping and oil and gas prices surging because of attacks on production facilities and tankers, and Iran’s threats to close the Strait of Hormuz.

Here’s what we’re covering:

• Global markets: Brent Crude, the global oil benchmark, rose above $80 a barrel, its highest level since 2024, and gasoline prices in the United States jumped 11 cents per gallon overnight. The S&P 500 opened almost 2 percent lower, following sharp stock market declines in Asia and Europe.

• U.S. advisory: The State Department urged Americans to depart immediately from 14 Middle East countries. The advisory cited “serious safety risks” and included Iran, Israel, Saudi Arabia, Qatar and the United Arab Emirates, along with Bahrain, Egypt, Iraq, Jordan, Kuwait, Lebanon, Oman, Syria, Yemen and the Palestinian territories. The State Department separately ordered nonessential staff members and their families to evacuate six countries: Bahrain, Iraq, Jordan, Kuwait, Qatar and the United Arab Emirates.

• Southern Lebanon: Israel Katz, the Israeli defense minister, said the country’s forces had been ordered to advance and take control of additional strategic locations in Lebanon to prevent Hezbollah attacks on Israeli border communities.

• Death toll: Iran’s Red Crescent Society, the country’s main humanitarian relief organization, said on Tuesday that the death toll had risen to 787 since the start of the U.S.-Israeli attacks on Saturday. The Pentagon said that six U.S. service members had been killed in the conflict and the Lebanese health ministry said that at least 31 people had been killed in fighting. In Israel, at least 10 people have been killed, and in the Gulf, there have been six deaths since Saturday, according to the authorities.