Donald Trump has warned NATO that it faces a ‘very bad future’ unless its member states help to keep the Strait of Hormuz open to global oil shipments. The waterway is a critical route for around 20% of the world’s oil, and disruption there has already heightened fears of economic instability. European nations now face a difficult choice between maintaining alliances and avoiding deeper involvement in the widening conflict, which Trump started without consulting his allies. Closing the strait was always seen as one of Iran’s main weapons, and Trump’s expectations that destroying the Iranian navy would prevent that from happening have proved unjustified: just by threatening drone strikes on tankers, Iran has effectively closed the strait and driven up oil prices. Trump wants NATO to send warships to escort convoys through the strait, which they are reluctant to do; he has now appealed to China, South Korea, Japan, and Australia to help. Other military options could further escalate the conflict, particularly if key infrastructure becomes a target.