After relatively successful trips to Riyadh, Jerusalem and the Vatican, American president Donald Trump's trip to Brussels always promised to be more difficult – even before the terrorist attacks in Manchester, which has strained co-operation between American and European allies.
Despite signs that Trump had softened his campaign rhetoric on Nato – he recently rowed back on his description of the alliance as "obsolete" – he delivered a stern message to the US's fellow Nato members as he stood alongside them at the organisation's headquarters on Thursday, publicly calling on members to increase their financial contribution to the alliance.
The decision to mark Trump's visit by unveiling a memorial to the September 11th attacks at the new Nato headquarters on the eastern fringes of Brussels was shrewd, acting as a not-so-subtle reminder of the article 5 principle that an attack on one Nato member is an attack on all. That principle of collective responsibility was invoked for the first and only time in the wake of the 2001 attacks, when European allies came to the side of the United States.
Trump's call on Europe to contribute more to Nato is nothing new – President Barack Obama made similar demands – although the public nature of Trump's comments may irk many. Privately though, some European leaders may welcome his comments, which will be used to justify increases in defence spending in their own countries.
The Russian problem
Of more concern to European members of the 28-member alliance is the growing gulf between the European members of Nato and the United States on the purpose and vision for the postwar institution. In particular, Europe remains miles apart from the Trump administration on the question of Russia.
Trump’s conciliatory approach to the Kremlin, epitomised by the sharing of classified information with the Russian foreign minister and ambassador in the Oval Office earlier this month, has alarmed European allies, particularly those in the east that fear Russian aggression.
Nato, after all, was created after the second World War as a counterbalance to the Soviet Union. While events have moved on, Russia's incursion into Ukraine and annexation of Crimea in 2014 has focused Nato's attention on countering the Russian threat.
The other key strategic issue preoccupying Nato members currently is Afghanistan.
Despite signs from the White House and the Pentagon earlier this month that the US would sanction the deployment of thousands of extra troops to the conflict to coincide with the May 25th Nato meeting, senior American officials are now reportedly split on the issue.
Defence secretary James Mattis – an increasingly important behind-the-scenes figure who sat at Trump's side at Thursday's meeting with EU Council president Donald Tusk and European Commission chief Jean-Claude Juncker – favours dispatching up to 5,000 more troops, but other advisers to the president are wary of committing more resources to the 16-year war.
About 13,600 Nato troops are serving in the country, about 8,600 of whom are American, but the US’s main commander in Afghanistan told a Senate committee earlier this year that more troops are needed to avoid a stalemate in the country.
Manchester attack
In many ways the question of further engagement in Afghanistan was overshadowed by the terrible events in Manchester. The attacks turned the focus of the summit towards the fight against terrorism, with Nato issuing a formal declaration of intent to fight Islamic State.
Although the escalating tensions between London and Washington over the apparent leaking of sensitive photographs by US intelligence overshadowed the meeting, the controversy may be welcomed by Trump for domestic political reasons.
The White House has railed against the US intelligence community for months. British fury at the leaking of information related to the Manchester attacks thus helps to vindicate the administration, which has been trying to focus on the leaking of information regarding the Russian investigation rather than the matters of substance.
The latest controversy over the leaking of information reveals a complete breakdown of trust – not simply between Britain and the United States, but between the White House and the US intelligence community. It seems unlikely that the Department of Justice review ordered by Trump will resolve the issue.