Tens of thousands of anti-Israel demonstrators flooded streets in more than a dozen countries Friday, clashing with police and burning US and Israeli flags in condemnation of the military counteroffensive underway in Gaza. The protests were part of a so-called “day of jihad” demanded by former Hamas leader Khaled Meshaal, who urged Arabs and Muslims around the world to “deliver a message of anger that we are with Palestine” after weekly prayers. Meshaal — who led the Islamist militant group from 2004 to 2017 — currently serves as head of the Hamas diaspora office in Qatar. He called it a...