Iran on notice.

One of the U.S. military's largest aircraft carriers arrives in the Middle East after thousands of Iranian protesters are killed in a brutal crackdown.

These were the largest, most widespread and deadliest protests since the 1979 revolution.

How vulnerable is the regime?

And what are President Trump's options if he chooses to enforce his red line

tonight on Compass Points?

Hello and welcome to Compass Points. This is an inflection point for Iran, the United States,

and perhaps the entire Middle East. The Iranian protest that began last month have been

unprecedented. Urban, rural, middle, and working-class Iranians by the hundreds of thousands

took to the streets, an eruption of economic frustration

that became a demand to bring down the regime.

The last time Iran experienced such widespread unrest

and found itself this vulnerable

47 years ago this month,

the historic 1979 revolution

when the Shah fell and gave way to the Ayatollah.

The Iranian crackdown killed thousands.

President Trump drew a red line,

and now the USS Abraham Lincoln is in the region.

Iran is threatening regional war against Israel, U.S. allies,

and more than 35,000 American service members,

all within striking distance of Tehran.

...