A crackdown on nationwide protests in Iran has killed at least 538 people and even more are feared dead, activists said Sunday, while Tehran warned that the U.S. military and Israel would be “legitimate targets” if America uses force to protect demonstrators.

Another over 10,600 people have been detained over the two weeks of protests, said the U.S.-based Human Rights Activists News Agency, which has been accurate in previous rounds of unrest in Iran in recent years. It relies on activists in Iran crosschecking information.

With the internet down in Iran and phone lines cut off, gauging the demonstrations from abroad has grown more difficult.

The Iranian government has not offered overall casualty figures for the demonstrations. The Associated Press has been unable to independently assess the toll, given that internet and international phone calls are now blocked in Iran.

Those abroad fear the information blackout is emboldening hard-liners within Iran’s security services to launch a bloody crackdown. Protesters flooded the streets in the country’s capital and its second-largest city again Sunday morning.

U.S. President Trump offered support for the protesters, saying on social media that “Iran is looking at FREEDOM, perhaps like never before. The USA stands ready to help!!!”

Trump and his national security team have been weighing a broad range of potential responses against Iran including cyberattacks and direct strikes by either U.S. or Israel, according to two people familiar with internal White House discussions who were not authorized to comment publicly and spoke on condition of anonymity.

The White House, which did not immediately respond to a request for comment, has not indicated it has made any decisions. The massive ongoing U.S. military deployment to the Caribbean has created another factor that the Pentagon and Trump’s national security planners must consider.

The threat to strike the U.S. military and Israel came during a parliamentary speech Sunday from Mohammad Baagher Qalibaf, the hard-liner speaker of the body who has run for the presidency in the past.

He directly threatened Israel, “the occupied territory” as he referred to it, and the U.S. military, possibly with a preemptive strike.

“In the event of an attack on Iran, both the occupied territory and all American military centers, bases and ships in the region will be our legitimate targets,” Qalibaf said. “We do not consider ourselves limited to reacting after the action and will act based on any objective signs of a threat.”

Lawmakers rushed the dais in the Iranian parliament, shouting: “Death to America!”

It remains unclear just how serious Iran is about launching a strike, particularly after its air defenses were destroyed during the 12-day war in June with Israel. Any decision to go to war would rest with Iran’s 86-year-old Supreme Leader Ayatollah Ali Khamenei.

The U.S. military has said in the Mideast it is “postured with forces that span the full range of combat capability to defend our forces, our partners and allies and U.S. interests.” Iran targeted U.S. forces at Al Udeid Air Base in Qatar back in June, while the U.S. Navy’s Mideast-based 5th Fleet is stationed in the island kingdom of Bahrain.

Israel, meanwhile, is “watching closely” the situation between the U.S. and Iran, said an Israeli official, who spoke on condition of anonymity due to not being authorized to speak to journalists. Israeli Prime Minister Benjamin Netanyahu spoke with U.S. Secretary of State Marco Rubio overnight on topics including Iran, the official added.

“The people of Israel, the entire world, are in awe of the tremendous heroism of the citizens of Iran,” said Netanyahu, a longtime Iran hawk.

At the Vatican, Pope Leo XIV mentioned Iran as a place “where ongoing tensions continue to claim many lives.”

“I hope and pray that dialogue and peace may be patiently nurtured in pursuit of the common good of the whole of society,” he said.