Once Donald Trump steps into Nato's headquarters in Brussels he will hope that he can navigate a tricky gathering with nervous European allies in a similar way to his meeting with Pope Francis in the Vatican.
Mr Trump's penchant for outlandish and dismissive statements meant that before his arrival in Europe, both the meeting in Brussels and the audience with the Pontiff, were being dissected for their potential for awkwardness. But while there were moments of obvious disagreement between Pope Francis and Mr Trump – namely a pointed gift from the Pontiff of a papal letter on climate change for the US President to read, given his previous statements declaring it a "hoax" – both appeared visibly more jovial after their 30 minute private meeting.
For Mr Trump's Nato allies the issue has been the uncertainty the commitment of the US to the group, particularly after Mr Trump labelled it "obsolete" and ill-equipped to fight terrorism, but that stance has softened and in the wake of the attack in Manchester, both sides appear keen to try and find common ground.
As with the meeting for the Pope, which centred on a call for Mr Trump to pursue peace, something the President said he was "determined to do", the Nato mini-summit will focus on fighting terrorism, one of Mr Trump's main pledges.
There will also be a number of mutual assurances given following months of uncertainty over Mr Trump's commitment to Nato since his inauguration. The President has repeatedly pushed for Nato allies to commit to a greater role in combating terrorism, including joining the coalition fighting against Isis in Syria. He has urged Nato allies to assume a greater share of defence spending.
Mr Trump repeatedly complained about the financial burden that the US takes on in ensuring the security of the alliance during his presidential campaign. Those comments created concern among European allies fretting about escalating Russian aggression and the repeated terror attacks faced by member states. Mr Trump’s silence on whether or not he would endorse Nato’s mutual defence pledge, known as Article 5, has further added to that trepidation.
Mr Trump pulled back from his “obsolete” comments last month, and he is expected to publicly break his silence on Article 5 in Brussels this week.
“Of course we support Article 5,” Secretary of State Rex Tillerson told reporters after landing in Brussels with Mr Trump. “The only time Article 5 has been invoked was in 9/11.”
Article 5 was invoked for the first and only time soon after the September 11 terrorist attacks in the US, and saw Nato allies deploying several counter-terrorism operations including the deployment of a larger naval presence in the Eastern Mediterranean to monitor shipping and trafficking. Nato allies also assisted US defence by flying radar aircraft missions in American airspace.
That US commitment to mutual defence has been of particular concern for Baltic member states who have experienced increased aggression from Russia, which annexed Crimea from Ukraine in March 2014, claiming it was protecting citizens from a conflict that is still raging in eastern Ukraine. A swirling scandal back in the US surrounding Mr Trump’s campaign’s potential ties to Russia have only added to the concerns.
Mr Tillerson, however, said in Brussels that the US remained convinced that Russia should move forward with the 2014 Minsk cease fire agreement in Ukraine and move toward restoring Ukrainian sovereignty.
“They are going to have to address the situation in Ukraine and we have been pretty clear with them what that means,” Mr Tillerson said when asked if it is still appropriate for Russia to be sidelined at G7 summits, one of which Mr Trump will attend later in the week in Sicily. “It means moving forward with the Minsk accord and restoring Ukraine sovereignty."
To show Mr Trump that Nato is responding to his calls to take on a greater role in combating terrorism, France and Germany are expected to agree to a US plan for Nato to take on a bigger role in fighting Isis and join the coalition fighting the terror group in Syria. French and German leaders have, however, indicated that the commitment is purely symbolic.
An anti-terror coordinator may also be named, but most changes will be cosmetic, as Nato allies have no intention of going to war against Isis. “It's totally out of the question for Nato to engage in any combat operations,” NATO Secretary-General Jens Stoltenberg said Wednesday, on the eve of the meeting.
“Nato as an institution will join the coalition,” a senior diplomat involved in those discussions told Reuters. “The question is whether this is just a symbolic to the United States. France and Germany believe it is.”
Mr Tillerson said that the President also plans on pushing Nato allies to fulfil their financial commitments to the alliance. Just five of 28 allies have met a 2014 agreement to spend at least 2 per cent of their gross domestic product on defence. The US is one of those countries.
“As the president has said, he really wants participating Nato members to step up and fully meet their obligations of the burden sharing,“ Mr Tillerson said. ”Two per cent of GDP was a target they all agreed to. I think you can expect the president to be very tough on them, saying: ‘Look, the US is spending 4 per cent. We're doing a lot. The American people are doing a lot for your security for our joint security. You need to make sure you're doing your share for your own security as well.’”
However, this will not be easy - with Germany already making clear that it cannot afford to spend double
Aside from security and financing concerns, American officials may hear from Nato allies who have written a series of reports in recent weeks highlighting the risks poised by climate change. Those countries have urged the Trump administration to respect the Paris Climate Agreement and to ensure that the US meets its commitments to reducing greenhouse gas emissions. It will certainly be a topic for the G7 summit on Friday.
Pope Francis made clear he sees climate as a priority for Mr Trump in gifting him a signed copy of his 2017 peace message whose title is “Nonviolence - A Style of Politics for Peace”, and a copy of his 2015 encyclical letter on the need to protect the environment from the effects of climate change. “Well, I'll be reading them,” Mr Trump said.
After Mr Trump flew from Rome to Belgium, the countries Prime Minister Charles Michel said he also insisted that Mr Trump should unequivocally back the Paris Agreement on climate change.
It is clear that there are a number of delicate issues facing Mr Trump on the latest leg of his first foreign trip - but having told Pope Francis "we can use peace" and come away from their meeting declaring that it went "great" and the Pontiff "is something... he is really good" - Mr Trump will hope he can emerge of the Nato mini-summit similarly unscathed.
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