American, Israeli and Lebanese officials insist that few parties want Israel's war in Gaza to become a larger conflict sweeping the Middle East.
But the assassination of a top Hamas leader in Lebanon on Tuesday and the deaths of scores of people in mysterious twin explosions in Iran on Wednesday threatened to push the Middle East – and the United States – closer to the brink of a regional war that the Biden administration has been threatening since tried to prevent Hamas' deadly attacks against Israel on October 7th.
Just hours after the bombs exploded in Iran, the United States and 12 of its allies sent a written warning to another militia group in the region, Yemen's Houthis, who carry out almost daily missile, drone and sea attacks on commercial airliners.
So far, the United States has refrained from retaliating against Houthi bases in Yemen, largely because it did not want to undermine the fragile ceasefire in Yemen's civil war.
But now Biden officials are signaling that their patience is running out.
“Let our message now be clear: We demand an immediate end to these illegal attacks and the release of the illegally detained vessels and crew,” White House officials said in a statement Wednesday, a day after shipping giant Maersk announced a pause in operations in the Red Sea.
“The Houthis,” the statement continued, “will bear responsibility for the consequences if they continue to threaten lives, the global economy and the free flow of trade in the region’s vital waterways.”
The warning – which was also signed by Britain, Australia, New Zealand, Bahrain, Belgium, Canada, Germany, Denmark, Italy, Japan, Singapore and the Netherlands – stopped short of threatening military strikes. Over the weekend, the U.S. Navy sank three Houthi boats and killed all crew members when they fired on American helicopters that were coming to the aid of a Maersk cargo ship.
On Monday, Iran's navy announced the deployment of a fleet of warships to the waterway. The same day, Iranian Foreign Minister Hossein Amir-Abdollahian expressed “gratitude and appreciation” to a Houthi official visiting Tehran for the group's support of Hamas, state news agency IRNA reported.
A senior Iranian official said the deployment of the warships, joining an Iranian spy ship already in the region, was intended to signal Iran's support for the Houthis and raise the stakes. However, the official said Iran had no plans for the warships to confront U.S. naval vessels in the waterway.
President Biden has said he wants to avoid direct military attacks on the Houthis to prevent an escalation of a Middle East conflict.
“We remain extremely concerned, as we have been since the beginning of this conflict, about the risk of the conflict spreading to other fronts,” Matthew Miller, a State Department spokesman, told reporters on Wednesday.
Hezbollah, the powerful Lebanese militant group, has vowed that Tuesday's killing of Hamas leader Saleh Al-Arouri in a Beirut suburb would not go without response. A key Hamas ally, Hezbollah exercises de facto control over Beirut's southern suburbs, where the blast occurred, and has been involved in escalating clashes with Israeli forces for months.
The circumstances surrounding the explosions at a monument to former Iranian general Qassim Suleimani in Kerman, Iran, were more unclear. While Iran was quick to blame Israel, European and American officials said they doubted the Israelis carried out the attack: Most of their actions against Iran were highly targeted, from eliminating the main architect of Iran's nuclear program to detonating certain nuclear weapons and Missile facilities.
Three senior American officials and a senior European official said Wednesday that the Islamic State or another terrorist group was a possible perpetrator. While there is some evidence suggesting Islamic State involvement in the attack, officials cautioned that the assessment is preliminary and no final conclusions have been reached.
“It is entirely possible that one of the Israeli proxy groups allowed an attack to get out of control,” Ray Takeyh, a senior fellow at the Council on Foreign Relations who often writes about Iran, said Wednesday.
Ayatollah Ali Khamenei, Iran's supreme leader, issued a statement on Wednesday blaming the country's “malicious and criminal enemies” for the attack, but refrained from naming any group or country. Mr Khamenei vowed that Iran's enemies should know that “this tragedy will provoke a strong reaction”.
Two people familiar with Iran's internal discussions said the ayatollah had ordered Iranian military commanders to exercise “strategic patience” and avoid Iran's direct military confrontation with the United States.
Several American officials said it was too early to predict whether a major war would break out. Israel, the officials said, would not have attacked Mr. Al-Arouri without the belief that it could do so without escalating the conflict on the border with Lebanon. But because the explosions, whatever their cause, occurred so quickly after the assassination, there was little doubt that the threat of escalating conflict in the United States and Europe was once again at the forefront.
Israeli officials did not comment on whether their forces had targeted Mr. Al-Arouri, but Lebanese and American officials attributed the attack to Israel.
After the attack, Biden administration officials planned to step up diplomatic efforts with officials in Lebanon to pressure Hezbollah not to escalate the conflict. In the coming days, Secretary of State Antony J. Blinken is expected to travel to the Middle East, where containing a possible escalation will be one of his key goals.
“The likelihood of a regional war in the Middle East increases from 15 percent to as much as 30 percent,” said retired Admiral James Stavridis, the former NATO commander. “Still relatively low, but higher than before and certainly uncomfortably high.”
But Biden administration officials and Middle East analysts noted that while Hezbollah and Iran have carried out skirmishes and proxy attacks against Israel, they are not necessarily eager to expand the conflict.
“During the devastation in Gaza, Hezbollah has insisted that it will engage in a limited capacity” to tie down some of the Israeli forces near Lebanon, Paul Salem, the president of the Middle East Institute, said in an interview. “It was crystal clear that they were not joining the fight directly.”
He and other analysts said that while Iran helped plan and orchestrate some of the attacks in the Middle East – including Houthi rocket attacks on ships in the Red Sea – it did not directly target the United States or Israel .
Mr Biden and his top aides have been trying to contain the conflict between Israel and Hamas in the Gaza Strip since the October 7 attacks. The Pentagon sent two aircraft carriers and doubled the number of American fighter jets to the Middle East to deter Iran and its proxies in Lebanon, Yemen, Syria and Iraq from escalating the war. Now this strategy is faltering. One of those aircraft carrier groups, led by Gerald R. Ford, is leaving the area, the Pentagon said this week.
Iran-backed militias have attacked U.S. troops deployed to combat terrorism in Iraq and Syria 118 times since the Oct. 7 attacks, most recently on Monday. Several U.S. soldiers were injured in the attacks, at least one critically, prompting the Pentagon to launch five retaliatory airstrikes against the groups.
In recent weeks, the Biden administration has declassified intelligence indicating that Iranian paramilitary groups coordinated the Houthi attacks and provided targeted intelligence on commercial ships passing through the waterway and the Suez Canal. Israel is heavily dependent on shipping traffic in the Red Sea.
In response to the attacks, the United States established a multinational naval task force to protect merchant ships in both the Red Sea and the Gulf of Aden.
Pentagon officials have drawn up detailed plans for attacks on missile and drone bases in Yemen, and some of the facilities where speedboats like those used to attack the Maersk container ship appear to be moored. But there are fears that such attacks would contribute to Iran's strategy of cornering Israel and its allies on multiple fronts.
“The loss of someone so closely involved in both tactical operations and strategic diplomacy is a major setback for Hamas,” Hanin Ghaddar and Matthew Levitt wrote in an analysis for the Washington Institute for Near East Policy. “It remains to be seen how the group’s allies, particularly Hezbollah, respond to the attack.”
Western leaders tried to contain rapidly rising tensions. French President Emmanuel Macron said shortly after the attack that it was “essential to avoid any escalatory stance, especially in Lebanon.”
In a phone call with Benny Gantz, an opponent of Israeli Prime Minister Benjamin Netanyahu who joined the country's unity government during the war, Mr. Macron said: “France will continue to convey these messages to all actors directly or indirectly involved in the region.” “, says a summary of the French Presidency’s call.
Farnaz Fassihi reported from New York and Michael Crowley from Washington.