There are two divergent views of Jake Sullivan, the US national security advisor and the most senior American to show up in person in Davos this year. One sees a formidably informed workaholic who hasn’t just kept Biden in the loop on everything from Taiwan to Tel Aviv but has also helped reshape US foreign policy and restore America’s global standing after the hammering it took under Trump. The other sees a problem: an inexperienced, over-cautious technocrat in a post that, now more than ever, requires vision, courage and serious powers of persuasion. That is the view shared by vocal allies of Ukraine who blame Sullivan more than Antony Blinken, the US secretary of state, for delays in getting game-changing weaponry to the Ukrainian front line and for what they consider a wrongheaded compartmentalisation of Russia’s war and the one not yet declared over Taiwan. “They’re linked, and he doesn’t get it,” one former US ambassador said. In this view the linkage takes the form of an imperative to defeat Russia in the west in order to deter China in the east. As of January 2024, both goals feel a long way off.