A delegation of NATO member-state ambassadors has visited Japan in what officials described as an unusually large-scale mission to observe security cooperation between Tokyo and Washington. The visit comes as US President Donald Trump has expressed frustration with NATO (the North Atlantic Treaty Organisation, a transatlantic military alliance), prompting allies to seek lessons from Japan's approach to managing its partnership with the United States. One participating ambassador told NHK that the trip made clear "how concretely Japan cooperates with the US and how important that is for America," suggesting Japan's alliance management could offer useful insights for European partners navigating an uncertain relationship with Washington.