Whilst the diplomatic studies field has grown impressively in the past decade, paradoxically there is much still to be learnt about 'state foreign services', a term covering the two sides of the diplomacy coin: diplomats serving at home-in the Foreign Ministry-and abroad-at embassies and consulates. Diplomats have a Janus-faced view of their profession: as envoys abroad and bureaucrats at home. This analysis first assesses the American approach to diplomacy's two sides, focusing on the impact of the Donald Trump presidency as a benchmark. Flowing from this are several key challenges that bedevil virtually all democratic foreign ministries: How to frame the 'national interest'? How to represent blemished or populist leaders? How to deal with dissent? How to balance the field-headquarters nexus? And how to manage relations with non-state actors. So long as the Westphalian state system survives, so, too, will the two-sided foreign-service model. Only when moving away from diplomacy as 'state practice' to diplomacy as 'social practice' can the foreign-service model recede, with diplomacy becoming disintermediated, omnilateral, and post-Westphalian, potentially manifesting radically different practices.