In the course of a week, several setbacks for President Bashar al-Assad have provided fresh reminders of the strains facing the Syrian army and its allies in the four-year-long struggle for Syria.

In the southwest at the border with Jordan, the capture of a crossing by rebels suggests new resolve among their Arab backers who want to see Assad gone and to check the growth of Iranian influence across the Middle East.

In the northwest, near the border with Turkey, the capture of an entire city by Islamist groups including al Qaeda’s Syrian wing has triggered claims in Damascus that Ankara has boosted its support for the insurgency. […]