This paper investigates the international externalities associated with US use of antidumping (AD) measures by examining the relationship between US AD duties (ADDs) and Japanese exports to the US and EU over the 1992-2001 period. We first examine the trade destruction and trade diversion associated with Japanese exports to the US market resulting from US AD duties. We then investigate whether US ADDs impose externalities on a non-targeted third country by examining the effect of these US policies on Japanese exports to the EU. We document sizable trade deflection and trade depression in the EU market resulting from US ADDs. Model estimates indicate that, on average, roughly one quarter to one third of the value of Japanese exports to the US thought to be destroyed by a US ADD is actually deflected to the EU in the form of a contemporaneous increase in exports. Finally, we present evidence that US ADDs impose terms-of-trade externalities on non-targeted markets. We find that US duties on Japanese exports are associated with substantially lower Japanese export prices in the EU market.