One of the most consequential policy shifts of the Trump administration followed its reappraisal of U.S. national security threats in December 2017. The administration's National Security Strategy lays out a vision for protecting the country and advancing American influence. The 2018 National Defense Strategy -- mostly classified -- provides guidance to the Department of Defense on how to execute it. The rogue regimes of Iran and North Korea, as well as jihadist terrorism, are identified as high priorities. But the biggest threat is strategic competition with China and Russia. The new era of great power competition may not feature direct warfare among the United States, China and Russia. Reliance on the use of proxies in the theaters of conflict will militate against that scenario. But conflict will arise in countries where it didn't exist before, and conflict will deepen in some where it already exists. In both cases, instability will...
