As Iran retaliates, largest US military base in Middle East hit by ballistic missile, Qatar says

Several neighbouring countries -- including Qatar, Saudi Arabia and Kuwait -- condemned a strike on the port of Duqm in Oman on Sunday.

The attack was the first apparent strike on Oman since the start of the conflict on Saturday.

Qatar called the reported attack "an unacceptable escalation and a cowardly targeting of a country playing an active role in mediation efforts."

Qatar itself reported attacks on Sunday "involving drones and cruise missiles launched by Iran." The country's Interior Ministry reported a fire in an industrial area caused by falling debris.

Elsewhere, the Kuwaiti Ministry of Defense said it "confronted a number of hostile aerial targets" on Sunday morning.

The United Arab Emirates and Bahrain also reported fresh Iranian attacks on Sunday.

-ABC News Victoria Beaule

A spokesperson for the Chinese Foreign Ministry on Sunday described the U.S.-Israeli killing of Iranian Supreme Leader Ali Khamenei as "a grave violation of Iran’s sovereignty and security."

"It tramples on the purposes and principles of the U.N. Charter and basic norms in international relations," the spokesperson said. "China firmly opposes and strongly condemns it."

"We urge for an immediate stop to the military operations, no further escalation of the tense situation and joint effort to maintain peace and stability in the Middle East and the world at large," the spokesperson added.

-ABC News’ Karson Yiu

The U.S. Embassy in Amman, Jordan, issued a shelter-in-place order for all mission personnel, telling them to avoid the Embassy compound "as it may be targeted."

"All Americans should exercise increased vigilance and avoid the U.S Embassy facility," the Embassy said in a post to X.

Protests have erupted at several U.S. diplomatic facilities in the Middle East and South Asia following the launch of the U.S.-Israeli operation against Iran on Saturday.

-ABC News’ Kevin Shalvey

Iran’s Guardian Council announced on Sunday that it had selected Ayatollah Alireza Arafi to join the three-person temporary leadership council formed to lead Iran following the killing of Supreme Leader Ali Khamenei.

Arafi will join President Mahmoud Pezeshkian and the head of the Iranian judiciary on the council.

-ABC News’ Somayeh Malekian and Victoria Beaule