Children were the first victims of the Syrian regime's crackdown that began in March 2011. In the city of Daraa, schoolchildren were detained and tortured for scrawling graffiti expressing opposition to President Bashar al-Assad.

By February 2012, Syrian forces had killed 500 children, according to Navi Pillay, the UN human rights chief. "They've gone for the children -- for whatever purposes -- in large numbers," Pillay told the UN Human Rights Council, as she appealed once again for the UN Security Council to refer Assad to the International Criminal Court for crimes against humanity.

Last weekend's massacre of at least 49 children among the more than 120 killed in Houla was part of the same pattern of targeting youngsters that has been central to Assad's murderous response to any dissent from his rule. The coordinated decision of Australia, Canada, France, Germany, Italy, Spain and the United States to expel Syrian diplomats expresses their genuine revulsion at the Houla massacre and Assad's adamant denial of responsibility, but such punitive diplomacy is not enough.