China is accused of conducting disinformation campaigns on Taiwan's social media. Existing studies on foreign interventions in democratic societies predict that such disinformation campaigns should lead to increasing partisan polarization within Taiwan. We argue that a backlash effect, making Taiwan's citizens more united against China, is equally plausible. We conduct a survey experiment exposing participants to a real-life rumour and rebuttal to test these competing hypotheses. We find, at best, mixed evidence for polarization. Although neither rumour nor rebuttal mention China, there is consistent evidence of backlash against China. Most notably, participants across the political spectrum are more inclined to support Taiwanese independence after viewing the rumour rebuttal. These findings indicate that citizens may put aside partisanship when confronted with false news that is plausibly linked to an external actor. We conclude by discussing the broader applicability of our theory and implications for cross-Strait relations.