This research proposed that social media use in public diplomacy should first be a strategic issue management (SIM) process. Using two case studies, the research identified four phases of the SIM process, namely the issue fermenting and going viral phase, the proactive phase, the reactive phase, and the issue receding and new issue fermenting phase. Social media are largely tactical tools in the first and the last phases. But they may become strategic tools in the proactive and reactive phases, in which diplomats may use them to reinforce a favorable viral trend, to build an agenda, and to respond to a conflict. In addition, the SIM approach argues that engagement, the Obama administration’s diplomatic doctrine, should be reassessed in a mixed-motive framework instead of being narrowly equated to dialogue.