Two decades of counterinsurgency wars have taken a toll on the US Army's proficiency in tank gunnery and mechanized warfare.

Rebel forces ... “a real bastion of military resources,” said Charles Lister, director of the Syria program at the Middle East Institute, a Washington-based think tank. Lister told NBC News ...

Sultani Makenga, an ethnic Tutsi rebel leader sanctioned ... into the Congolese army, “this time it has a national agenda,” the Crisis Group think tank said of M23 in a recent assessment.

Then in late January, a group of rebel leaders appointed Mr. al-Shara president, and he has since vowed to dissolve the country’s many former rebel groups into a single national army.