(CNN) With missiles at their borders and neighbors aligning with an adversary, China and Russia could feel boxed in. "We think the US-South Korean decision to deploy the THAAD missile defense system has seriously threatened China's security interest. "It's natural and logical for China and Russia to take a joint position," says Victor Gao, director of the China National Association of International Studies, citing that THAAD's range. The joint opposition to the system has drawn Russia and China closer militarily, as both countries worry that it'll box them in. Buried in this year's National Defense Authorization Act was an amendment to the 1999 National Missile Defense Act.

Source: CNN January 13, 2017 08:01 UTC