Diplomacy is essential for mediating between states to find resolution, compromise, and agreement, often in challenging situations, with grace and foresight. The language of diplomacy requires subtlety and skill, and sometimes opacity to enable differing opinions to surface and alternative conclusions to be reached. To skilfully apply this instrument, it is a virtue to avoid insult and to settle differences by peaceful and respectful means, and to avoid unnecessarily inflaming passions. Bullshit, a deceptive method which aims at manipulating the opinions and attitudes of those with whom the bullshitter speaks, with no regard for the truth, can be no part of this art. Yet, as I will argue here, the U.S. president Donald Trump all too often engages in bullshit and lies in his dealings with international states. Trump confidently, even bombastically, asserts his success and abilities on foreign policy issues and international negotiations; however, on closer analysis of social media, it is clear that Trump lacks these vital skills, frequently compromising agreement and undermining progress. This article examines the difference between bullshit and diplomacy by analysing Trump’s statements on social media platforms and concludes that Trump’s bullshit is a threat to diplomacy.