A harsh crackdown on protests in Iran has killed at least 538 people, with fears the actual number is even higher, activists said on Sunday. Over 10,600 people have been detained in just two weeks, according to the US-based Human Rights Activists News Agency. Iran's authorities have not given any official total deaths. Due to an internet blackout and phone restrictions, it is hard to verify the figures from outside the country. Despite this, protesters flooded streets in Tehran and Mashhad on Sunday, waving lit phones and banging metal objects. US President Donald Trump voiced support for the demonstrators, tweeting, “Iran is looking at FREEDOM, perhaps like never before. The USA stands ready to help!!!” Iranian parliament speaker Mohammad Baagher Qalibaf warned the US and Israel in a speech, saying, “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.” Lawmakers shouted “Death to America!” after his speech. It remains unclear if Iran plans military action. The US military said it is ready to defend its forces and allies in the Middle East. Israel said it is “watching closely,” and Prime Minister Benjamin Netanyahu praised the protesters' courage. Protests began on December 28 after Iran’s currency collapsed amid sanctions. What began as cost of living protests now calls for change to Iran's theocratic system. President Masoud Pezeshkian urged dialogue but also stressed stopping rioters from destroying society. Videos online show ongoing protests, despite security force presence, drones monitoring crowds, and roads blocked by police. Iranian officials blamed rioters for violence, comparing them to ISIS and reported more deaths among security forces. The unrest and crackdown continue under severe information blockades, leaving the world closely watching this heated crisis.