How fitting that the UK’s failed test firing of a Trident nuclear missile in June occurred as Donald Trump launched his Presidential campaign. President Trump has stated that he is not in favour of subsidising the cost of Europe’s nuclear weapons. The US-owned Trident missiles are leased to the UK under the terms of a mutual defence agreement. Once the bedrock of US/UK relations, this agreement no longer enjoys such an exalted status. There is increasing ambivalence on both sides and consequently the UK’s leasing of US nuclear missiles has every chance of spiralling off course.