One of Pope Francis’s top aides delivered a personal letter from the pontiff to Syrian President Bashar al-Assad, among other things expressing Francis’s “deep concern” for the humanitarian situation in Idlib, a rebel-controlled area in northwestern Syria that’s been the target of Russian-backed airstrikes since April.

A Vatican statement on July 22 indicated that Cardinal Peter Turkson of Ghana, who heads the Vatican’s department for Promoting Integral Human Development, met that morning in Damascus with Assad, accompanied by Italian Cardinal Mario Zenari, the Pope’s ambassador in Syria.

The statement, issued by new papal spokesman Matteo Bruni, said that the letter “expresses the deep concern of His Holiness Pope Francis for the humanitarian situation in Syria, with particular reference to the dramatic consequences facing the civilian population in Idlib.”

Airstrikes in Idlib alone left at least 17 civilians dead, including seven children, according to the Britain-based Syrian Observatory for Human Rights.

The observatory warned that the death toll could rise significantly as bodies are cleared from rubble.