AMNA NAWAZ: Welcome to the "News Hour."

Tonight, the State Department says all Americans should leave Iran, as protests there are entering their third week and tens of thousands of people continue to take to the streets despite a deadly crackdown.

President Trump tonight said that the death toll appears significant.

Western officials say at least 2,000 have been killed and perhaps many more.

That would make these protests the deadliest since the 1979 revolution and analysts say they could threaten the regime itself.

Nick Schifrin reports.

NICK SCHIFRIN: Today in Iran, defiance.

Protesters denounce the regime right in front of its security forces... (GUNSHOTS) NICK SCHIFRIN: ... despite live ammunition shot into the crowds, a brutal crackdown that Western officials say has been led not by police, but by the Islamic Revolutionary Guard Corps.

Estimates vary widely, but Western officials said today at least 2,000 have been killed, perhaps many times that.

This crackdown, combined with an Internet cutoff, has led to slightly fewer protests today and a climate of extreme fear, according to a man in southern Iran we spoke to today by phone whose name we are changing to Meherdad.

MEHERDAD, Iranian Protester (through translator): The protests are not as big as they were last week.

And from what I have heard from those in other towns, the protests are not as big since the crackdown.

I was going, but not since Saturday, because it was impossible to get to the streets.

NICK SCHIFRIN: Experts call these the most serious protests in Iran's history, combining rural and urban, working and middle-class Iranians.

And the ruthless response has in turn affected every Iranian.

MEHERDAD (through translator): Anyone you ask, they have family members, one or multiple, injured or killed.

In the past few days of the protests, their forces have been stronger, and anyone they see on the streets, they either shoot or do something else to make them go away.

DONALD TRUMP, President of the United States: To all Iranian patriots, keep protesting, take over your institutions if possible.

NICK SCHIFRIN: Today, in Detroit, President Trump vowed to avenge the dead by punishing the security forces who fired into the crowds.

DONALD TRUMP: Save their names, because they will pay a very big price.

And I have canceled all meetings with the Iranian officials until the senseless killing of protesters stops.

And all I say to them is, help is on its way.

NICK SCHIFRIN: He didn't define that help, but speaking to CBS News tonight, President Trump brought up previous U.S.

military strikes.

TONY DOKOUPIL, Host, "CBS Evening News": What's the endgame?

DONALD TRUMP: The endgame is to win.

I like winning.

And we're winning.

TONY DOKOUPIL: How do you define that in Iran?

DONALD TRUMP: Well, let's define it in Venezuela.

Let's define it with al-Baghdadi.

He was wiped out.

Let's define it with Soleimani.

NICK SCHIFRIN: The U.S.

is also working to help ensure activists can share these videos with the world by working with Starlink.

AHMAD AHMADIAN, Executive Director, Holistic Resilience: As of this morning, there are reports, confirmed reports that the Starlink subscription is lifted, so it's plug and connect.

NICK SCHIFRIN: Ahmad Ahmadian is the executive director of the Internet freedom organization Holistic Resilience.

He says there are as many as 50,000 Starlinks in Iran and eliminating subscription costs will help activists not only release videos, but also communicate with each other.

AHMAD AHMADIAN: People need to get this information from their leaders, from the coordinators outside of the Iran to be able to protect themselves and also have the instructions how to coordinate, how to mobilize, saying where are the areas that the protest is happening, and getting those information and working with those channels and reporters to broadcast those information back inside the country, so they know what to do and what to do next.

NICK SCHIFRIN: But what the regime is doing next, planning a public execution of protester Erfan Soltani.

They have already broadcast about 100 coerced confessions, an attempt to destroy the dissent that targets the regime and its sources of power.

For the "PBS News Hour," I'm Nick Schifrin.