Such high-level defections have been rare so far. But if they become more frequent, they could cause Assad's regime to crumble from within.
Russia plans to dispatch two ships carrying marines to its naval base in Tartous, reportedly to protect Russian citizens and evacuate them if needed.
The summit is intended to allow EU leaders to reacquaint themselves with President Vladimir Putin, but they are expected to lean on him to take a stronger stand on Syria.
This week's reading list includes a book review on how we use and abuse language, leadership tips from Genghis Khan, and a tribute to the late hip hop master and peace activist, Adam Yauch.
Letters to the Editor for the weekly print issue of May 7, 2012: John Bolton is wrong. Obama is protecting the US and world economy from a disastrous attack on Iran. It's Israel that has the nukes. And the best way to foment regime change in Iran is to support the opposition there.