The volunteer US military & America's shame post-Afghanistan

For Elliot Ackerman, leaving no man behind was part of his code of honor when he was first a US marine and later a CIA officer. But the US military principle was not followed when American troops departed Afghanistan a year ago.

"There was no process to get our allies out," he tells Ian Bremmer on GZERO World.

Ackerman laments how US forces were forced to turn their back on Afghans they'd cultivated personal relationships with for 20 years — when they most needed help.

He also shares his thoughts on whether an all-volunteer military is what America needs amid deeply dysfunctional domestic politics.

Watch the GZERO World episode: The fallout from US Afghanistan withdrawal: a Marine's perspective