Israel carried out a daytime assault on Tehran on Saturday, sending smoke billowing from the city center.

The initial strike targeted areas near the offices of Supreme Leader Ayatollah Ali Khamenei.

The United States is participating in the operation, though the exact scale of its involvement remains unclear, according to a U.S. official and a source familiar with the mission, who spoke on condition of anonymity due to the sensitivity of military operations.

It is not known whether the 86-year-old Khamenei was present at his offices during the attack.

He has not been seen publicly for several days amid escalating tensions with the United States.

The strikes come as Washington has deployed a large fleet of fighter jets and warships to the region to pressure Iran into a nuclear deal.

Authorities had closed roads leading to Khamenei's compound in central Tehran as other blasts were reported across the city.

US President Donald Trump had aimed for a deal to limit Iran’s nuclear activities and see a chance while the country faces rising domestic unrest following nationwide protests.

Iran had sought to avoid war but insists it has the right to enrich uranium and refuses to negotiate on other issues, including its long-range missile program or support for armed groups such as Hamas and Hezbollah.

It is unclear whether Iran will retaliate immediately, but Tehran has warned that American military personnel and bases across the region would be targets for any response.

Israeli Defense Minister Israel Katz described the strikes as being carried out “to remove threats.” He did not provide further details.

In Tehran, witnesses reported hearing the first blast near Khamenei's office. Iranian state television later covered the explosion without specifying a cause.

Sirens sounded across Israel as the country closed its airspace. The Israeli military said it issued a “proactive alert to prepare the public for the possibility of missiles being launched toward the state of Israel.”

Additional explosions were reported in Tehran following the Israeli attack, though authorities have not released casualty figures. Iran meanwhile closed its airspace and disrupted mobile phone services.

Warnings to pilots coincided with the blasts reverberating across the Iranian capital.