Tonight on PBS News Weekend, Iran warns of retaliation if the United States or Israel uses force to support anti-government protesters.

Then how social media lures people around the world seeking to migrate to undertake treacherous potentially fatal journeys.

And scientists are using new technology

to track individual monarch butterflies on their

transcontinental migrations.

After all these years of trying to understand

the migration of monarch butterflies,

now we really know exactly where they're going.

And it's just quite fascinating.

Good evening. As anti-government protests in Iran and the ruling regime's bloody

crackdown on them both intensify. Tehran warned the United States to stay out of it. White House

National Security advisors are said to be weighing a broad range of potential responses, including

direct military

strikes, to present to President Trump, who says he stands ready to help the protesters.

Today, the hardline Speaker of Iran's parliament said U.S. intervention could have dire consequences.

And I have a message for the delusional American president.

In order to avoid miscalculations, be aware that if you take action to attack Iran,

both the occupied territories in all U.S. military centers, bases, and ships in the region,

will be considered legitimate targets by us.

While numbers are hard to know with any certainty because Iran's internet and phone service

have blocked, human rights watchdog group told the Associated Press that more than 500 people

have been killed and 10,000 detained. Iran's top prosecutors said rioters would be dealt with

...