The U.S. government has announced that it will impose sanctions against top Syrian officials in response to the regime's violent crackdown on protesters, building on sanctions the U.S. already imposed on Syria during the Bush administration. The news comes amidst reports from activists that Syrian security forces have killed up to 50 people during today's "day of rage."

In a letter to Speaker of the House John Boehner, President Obama wrote, "I have determined that the Government of Syria's human rights abuses, including those related to the repression of the people in Syria ... constitute an unusual and extraordinary threat to the national security, foreign policy, and economy of the United States," according to CNN. The news outlet says the sanctions will involve asset freezes, travel bans, and prohibitions on conducting business in the U.S.

Here's who Reuters is saying the sanctions will target:

• Mahir al-Assad: The brother of Syrian leader Bashar al-Assad is a brigade commander in the army's 4th Armored Division, which has intervened in Daraa.
• Atif Najib: Bashar's cousin is the former head of the Political Security Directorate for Daraa.
• Ali Mamluk/Syrian intelligence agency: U.S. officials will impose sanctions on Mamluk and his agency suppressing opposition, keeping tabs on individual citizens, and having a hand in the deaths of protesters in Daraa.
• The Quds Force: U.S. officials believe this wing of Iran's Islamic Revolutionary Guard Corps, which is already a target of U.S. sanctions for supporting militant groups in Iraq and elsewhere, is supporting Syria's crackdown on protesters.

No sanctions yet for Assad himself, though Reuters says this latest batch of sanctions might prevent the Syrian leader from getting a luxury aircraft he was after. U.S. official tells Reuters that Obama is not yet calling for Assad to step down because he doesn't "want to get out in front of the Syrian people."

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Uri Friedman