The causes of current trade tensions are complex, but have their roots in widespread frustration that the international rulebook has not kept pace with economic and technological changes, and not everyone is playing by the existing rules. While there is no shortage of concerns – from border restrictions, and behind-the-border regulations that can impose unnecessary costs on traders, to new restrictions on the cross-border data flows that underpin trade in the digital era – particular attention has focused on government support that distorts international markets. This support is both long-standing – in the case of agriculture – and more recent - in the case of industrial products – but in both cases appears to be sizeable.