US-Israeli strikes on Iran reached their most intense day yet on Tuesday as mixed signals from Washington fueled uncertainty over when the conflict might end.

United States Defense Secretary Pete Hegseth told reporters on Tuesday that operations would continue "on our timeline" until "the enemy is totally and decisively defeated". Hours earlier, President Donald Trump said the war was "very complete, pretty much" and that the US was "very far ahead of schedule".

Meanwhile, Iran named Mojtaba Khamenei, the son of its slain supreme leader Ali Khamenei, as its new supreme leader on Monday.

Jack Midgley, principal consultant at Midgley & Company and an adjunct associate professor in the Security Studies Program at Georgetown University in Washington, said the conflicting messages appeared deliberate.

"The administration is sending many different messages to avoid being held accountable for any bad outcomes," Midgley said. "Hegseth's message pleases the Israelis and the US hardcore right, while Trump's message is intended for the international community and markets."

At a Brookings Institution webinar on March 3, Philip Gordon, a Sydney Stein Jr. Scholar at the institution and national security adviser to former US vice-president Kamala Harris, said the administration had struggled to articulate consistent goals, shifting from nuclear concerns to regime change and other aims.

"It's been a moving target," Gordon said.

A day earlier, at a Center for Strategic and International Studies discussion, Seth Jones, president of the Defense and Security Department and holder of the Harold Brown Chair at the center, warned that causing major damage to Iran from air and naval assets alone would be "very difficult".

Midgley said the US and Israel should de-escalate immediately to avoid further regional instability."The goal of denying nuclear weapons to Iran can only be reached with a negotiated settlement, and negotiations are unlikely to resume while Iran is under attack."

Tehran now lacks trust after the scale of the strikes, he said. "The barrier is that Iran cannot trust the US or Israel to negotiate in good faith. (It) was created by the massive scale and aggressive objectives of the US-Israel attack and not by the Iranian side."

On the question of naval protection through the Strait of Hormuz, Trump has said repeatedly in recent days that the US is prepared to escort tankers through the strategic waterway when necessary.

Midgley called the idea impractical because it would "place navy ships directly in range of Iranian anti-ship missiles and guns, potentially trading American lives for oil".

"The idea is both unworkable and politically unacceptable for Americans," he said.

The White House said on Tuesday that the US has not escorted any oil tanker through the strait, after Energy Secretary Chris Wright's social media account posted and deleted a claim that it did so.

At the Center for Strategic and International Studies event, Clayton Seigle, a senior fellow and James R. Schlesinger Chair in Energy and Geopolitics at the center, warned of serious energy risks even if fighting eased.

"We have seen both vectors for supply disruptions," he said, citing attacks on shipping and infrastructure such as Saudi Arabia's Ras Tanura refinery and Qatar's Ras Laffan LNG terminal.