When Iraq is losing territory to ISIS, the US sends more ground troops. When Iraq recovers territory from ISIS, the US is also sending ground troops, however, with Defense Secretary Ash Carter announcing 560 more ground troops being deployed to Iraq today after Iraq's weekend capture of the Qayara Air Base.

This brings the "official" number of US ground troops in Iraq to 4,617, well over the cap agreed to with the Iraqi government. That cap's been broken for awhile in practice, and the latest deployments are actually expected to bring the total US force to well over 6,000 troops.

On the Tigris River, the Qayara Air Base is in the southern part of Nineveh Province, and has been sought by Iraq for years as a base from which to launch the invasion of Mosul, the nation's second largest city and ISIS's largest.