Former Secretary of Defense Donald Rumsfeld on Thursday warned Syrian leader Bashar al-Assad and Iranian leader Mahmoud Ahmadinejad to watch their backs.

Rumsfeld, responding to reports that Libyan leader Moammar Gadhafi was killed after months of uprising, tweeted: “al-Assad & Ahmadinejad best heed this morning's news on Gaddafi. Their people may decide they should be next.”

Protests erupted in Syria seven months ago, with many wanting to oust the Syrian leader, Bashar al-Assad. The country has been facing continuous political instability since then.

Iran faces heightened scrutiny after U.S. announced last Tuesday that officials suspect that country of being behind the attempt to murder Saudi Arabia’s ambassador to the U.S. last Tuesday.