Lebanese soldier Ali Al-Sayyed was beheaded by Islamic State militants, a video released Saturday by the terrorist group shows.
Hasan wrote a letter to ISIS leader Al-Baghdadi, saying it would be an honor to be an ISIS "citizen soldier."
Van Rompuy says new sanctions against Russia will be drawn up within a week.
One issue centers on the Israeli blockade that impedes the cross-border movement into Gaza of building materials such as concrete.
Parents want Ashya to undergo proton beam therapy for his brain tumor.
Three weeks after the death of Mike Brown, hundreds gathered in Ferguson, Missouri, Saturday to march for the slain teen.
The experimental drug has so far cured two American doctors, but the company producing it says it has no more doses of the drugs.