The U.S. and Iran have entered a dangerous new phase of conflict after three days of clashes, including an Iranian drone downing an American Apache helicopter, a direct Iranian strike on Israel, and U.S. retaliatory strikes across the Gulf.

Monday evening’s incident off the coast of Oman brought the two sides close to the threshold for escalation that President Donald Trump has described in private conversations with aides: ending the ceasefire if Tehran kills American troops, according to officials familiar with the discussions. The Apache’s two crew members were rescued by a sea drone after spending hours in the water, a first-of-its-kind mission, officials said.

Iranian officials said Tehran did not deliberately target the helicopter, though Iran has been firing drones at commercial vessels coordinating with the U.S. to transit the Strait of Hormuz.

The three days of fighting marked the most serious escalation since Trump declared a ceasefire in the U.S. and Israeli bombing campaign against Iran in April, ending nearly 40 days of strikes that began Feb. 28. The pause followed a series of skirmishes centered on U.S. efforts to enforce a blockade of Iranian ports and Tehran’s actions to keep shipping bottled up through the strategic waterway.

“They’re managing the war, but they’re also trying to set the parameters of the ceasefire and win additional leverage through kinetic strikes,” said Dina Esfandiary, a longtime Iran analyst at Bloomberg Economics. “Despite the fact that neither side wants to continue it, I think both sides are prepared to continue it.”

Security analysts said the Apache incident could reflect risks in Iran’s defense doctrine, under which the Islamic Revolutionary Guard Corps delegates a high degree of freedom of action to commanders who can operate without direct orders from Tehran — an approach known as the “Mosaic” defense strategy.

“It is a very fragile situation. This equilibrium is not stable because of the risk of miscalculation and unwanted escalation,” said Hamidreza Azizi, a visiting fellow at the German Institute for International and Security Affairs. “The pattern on the Iranian side has been to keep the escalation below a certain threshold, and that threshold has been killing American soldiers and personnel during the ceasefire.”

Iran has shown some restraint, analysts said. It was first to publicly announce an end to the exchange with Israel and avoided crowing about the downing of the Apache as it had when other American aircraft were shot down. It avoided highly sensitive targets such as Israeli population centers and Saudi Arabia, and used relatively limited volleys of missiles and drones.

“I think that, yes, there was a kind of risk taken by the Iranians, but it doesn’t seem that Iran really wanted to be engaged in a full-scale confrontation with Israel,” said Raz Zimmt, director of the Iran research program at Israel’s Institute for National Security Studies.

Talks toward a diplomatic end to the war have not made progress despite weeks of comments by Trump that a deal is close. Trump expressed frustration over the lack of progress on social media Wednesday: “They’ve taken too long to negotiate a deal that would have been great for them, now they will have to pay the price.”

Mediators said the two sides are still hammering out key issues, including how soon Iran can expect financial relief and how specifically restrictions on its nuclear program will be addressed. The goal is a minimal memorandum of understanding to stop the fighting, open the strait, and set up talks on more difficult issues.

“The system absorbed the decapitation, consolidated around its new leadership, and now treats the confrontation as existential,” said Oral Toğa, a researcher at IRAM Center for Iranian Studies in Ankara. “Both sides need a narrative that allows them to de-escalate without looking as if they capitulated.”

The military standoff around the Strait of Hormuz — typically the transit point for much of the world’s oil and a key lifeline for Gulf Arab states — has brought U.S. military aircraft flying near Iranian drones and speedboats, creating a high risk of conflict. Iran’s regime emerged from the initial war militarily and economically battered but with new leverage from its hold on the strait and its ability to hold Gulf energy facilities at risk.

Going deeper: Read MSI’s analysis of US-Iran escalation dynamics →