Both South Korea and Turkey enjoy explicit nuclear guarantees. Yet under the Obama administration, relations with each have lurched to opposite ends of the ‘reassurance spectrum.’ As a result, both feel less secure than they should. For Seoul, the last eight years have been testing ones. South Korea’s territory and military have both been struck by North Korea, with Yeonpyeong Island shelled and the ROK’s Cheonan sunk in 2010. The DPRK’s nuclear program has developed apace, with three nuclear tests being conducted in 2009, 2013, and 2016. Most worryingly of all, North Korea’s assertive nature has not only survived the transition to Kim Jong-Un but intensified under his watch. There appears to be no end in sight. Washington’s response to these challenges has been to go out of its way to provide additional reassurance in the form of B-52 overflights at times of crisis, greater consultation on issues of extended deterrence, and added additional economic pressure against the DPRK in the form of economic sanctions. Thus far, these efforts have succeeded in reassuring the South to the extent that Seoul hasn’t felt it necessary to take concerted action of its own in response to the North Korean challenge. The opposite dynamic characterizes U.S. relations with Turkey. Under the Obama administration, Ankara has become accustomed to an American unwillingness to provide assistance. Be it help with establishing a no-fly zone in northern Syria to stem the flow of refugees, military action to topple the Assad regime, or clear action designed to punish Russia for its military intervention, the response from Washington has been negative. As a result, the Erdogan administration has shown an increasing willingness to take matters into its own hands, demonstrated most clearly by its downing of a Russian jet along its southern border in November of last year. Both situations risk provoking unwanted crises. The United States has been so keen to restrain the south in order to maintain calm on the Korean Peninsula that Pyongyang may soon come to conclude that Washington will always move to do so irrespective of how aggressive its behavior becomes. Any such calculation would greatly increase the prospect of a major escalation by the DPRK at some future point. At the same time, Washington has been so quick to rule out meeting Turkish requests for support that it risks losing control over the military policy of a key NATO partner, raising the prospect of the Alliance as a whole being dragged into a broader confrontation with Russia via Turkish unilateralism. The next administration should move to moderate these extreme positions. Applying a more hands-off policy in Korea, and in particular revisiting the transfer of operational control to ROK military forces during wartime, would strengthen deterrence by creating greater uncertainty in Pyongyang. At the same time, a more active approach that offers greater reassurance to Turkey, such as force deployments that create a safe haven for refugees within Syria, would help halt Ankara’s drift towards a unilateralist defense policy that could embroil NATO in an unwanted confrontation.