Strain on munitions

At the Brookings event, Mara Karlin, a visiting fellow at the Strobe Talbott Center for Security, Strategy and Technology, highlighted the strain on US munitions and readiness, saying prolonged operations could limit options elsewhere.

Midgley said the biggest long-term cost was eroding international trust in US leadership. "NATO European members and regional partners like Saudi Arabia and the United Arab Emirates are suffering real damage and were not consulted on American military moves," he said.

The US had set aside international law, including the United Nations Charter, he added. "As the US acts unilaterally, international confidence in US leadership continues to decline."

As of late Tuesday afternoon in Washington, no ceasefire was in sight. The Pentagon said strikes would continue, while the administration maintained the war was nearing its end. Oil markets remained volatile, and the risk of miscalculation in the Strait of Hormuz lingered.

The mixed signals from Washington could prolong the conflict "by creating confusion among allies and adversaries alike", Midgley said.

"Until there is a clear, unified US position on de-escalation, the path to a negotiated end remains blocked."

Agencies contributed to this story.