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.

In pictures: President Donald Trump on tour Show all 39 1 /39 In pictures: President Donald Trump on tour In pictures: President Donald Trump on tour 20 May 2017 US President Donald Trump and Saudi Arabia's King Salman bin Abdulaziz al-Saud arriving for a reception ahead of a banquet at Murabba Palace in Riyadh Getty Images In pictures: President Donald Trump on tour 20 May 2017 US President Donald Trump, accompanied by First Lady Melania Trump, and Saudi Arabia's King Salman bin Abdulaziz al-Saud being welcomed at Murabba Palace in Riyadh Getty Images In pictures: President Donald Trump on tour 20 May 2017 US President Donald J. Trump with King of Saudi Arabia Salman bin Abdulaziz Al Saud during a welcome ceremony with traditional sword dancers at Murabba Palace, in Riyadh, Saudi Arabia EPA In pictures: President Donald Trump on tour 20 May 2017 King of Saudi Arabia Salman bin Abdulaziz Al Saud with US President Donald J. Trump and wife Melania during a welcome ceremony at Murabba Palace, in Riyadh, Saudi Arabia EPA In pictures: President Donald Trump on tour 20 May 2017 US President Donald Trump adjusts the Collar of Abdulaziz Al Saud Medal, after it was bestowed upon him by Saudi Arabia's King Salman bin Abdulaziz Al Saud at the Royal Court in Riyadh, Saudi Arabia Reuters In pictures: President Donald Trump on tour 20 May 2017 Saudi Arabia's King Salman bin Abdulaziz Al Saud presents U.S. President Donald Trump with the Collar of Abdulaziz Al Saud Medal at the Royal Court in Riyadh, Saudi Arabia Reuters In pictures: President Donald Trump on tour 21 May 2017 Palestinians print posters depicting US President Donald Trump in preparations for his planned visit, in the West Bank town of Bethlehem Reuters In pictures: President Donald Trump on tour 21 May 2017 US President Donald Trump accompanied by first lady Melania Trump, his daughter Ivanka Trump and her husband White House senior advisor Jared Kushner, before delivering his remarks to the Arab Islamic American Summit in Riyadh, Saudi Arabia Reuters In pictures: President Donald Trump on tour 21 May 2017 US President Donald Trump looks on as U.S. Secretary of State Rex Tillerson and Saudi Arabia's Crown Prince Muhammad bin Nayef exchange a memorandum of understanding Reuters In pictures: President Donald Trump on tour 21 May 2017 First Lady Melania Trump shares a laugh with a child during a visit to the American International School in the Saudi capital Riyadh Getty Images In pictures: President Donald Trump on tour 21 May 2017 US President Donald Trump holds a bilateral meeting with Bahrain's King Hamad bin Isa Al Khalifa AP In pictures: President Donald Trump on tour 22 May 2017 Israeli soldiers rest during preparations ahead of President Trump's landing in Tel Aviv, Israel Getty Images In pictures: President Donald Trump on tour 22 May 2017 First Lady Melania Trump makes her way to board Air Force One in Riyadh as she heads with her husband the US President to Israel Getty Images In pictures: President Donald Trump on tour 22 May 2017 US President Donald Trump and first lady Melania Trump board Air Force One for Israel, the next stop in Trump's international tour, at King Khalid International Airport AP In pictures: President Donald Trump on tour 22 May 2017 Israeli soldiers wait for the arrival ceremony of US President Donald Trump at Ben Gurion airport near Tel Aviv, Israel AP In pictures: President Donald Trump on tour 22 May 2017 US President Donald Trump and first lady Melania Trump arrive aboard Air Force One at Ben Gurion International Airport in Lod near Tel Aviv, Israel Reuters In pictures: President Donald Trump on tour 22 May 2017 US President Donald Trump and first lady Melania Trump disembark Air Force One on arrival at Ben Gurion International Airport AP In pictures: President Donald Trump on tour 22 May 2017 US President Donald J. 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Trump, touches the Western Wall, Judaism's holiest prayer site, in Jerusalem's Old City EPA In pictures: President Donald Trump on tour 22 May 2017 President Donald Trump visits the Western Wall AP In pictures: President Donald Trump on tour 24 May 2017 US President Donald J. Trump arrives in a vehicle to Saint Damaso's Court for a private audience with Pope Francis in Vatican City EPA In pictures: President Donald Trump on tour 24 May 2017 Pope Francis walks past Ivanka Trump and First Lady Melania Trump on the occasion of the private audience with President Donald Trump, at the Vatican AP In pictures: President Donald Trump on tour 24 May 2017 Pope Francis exchanges gifts with US President Donald Trump during a private audience at the Vatican Getty Images In pictures: President Donald Trump on tour 24 May 2017 Pope Francis meets US President Donald Trump and his wife Melania during a private audience at the Vatican Reuters In pictures: President Donald Trump on tour 24 May 2017 Pope Francis with US President Donald J. Trump EPA In pictures: President Donald Trump on tour 24 May 2017 Pope Francis gets into is car after meeting with US President Donald Trump AP In pictures: President Donald Trump on tour 24 May 2017 President Donald Trump and his wife Melania look at the frescoed ceilings during their visit to the Sistine Chapel at the Vatican L'Osservatore Romano/Pool Photo via AP In pictures: President Donald Trump on tour 24 May 2017 US President Donald Trump security vehicles are seen in front of Air Force One before take off from Leonardo da Vinci-Fiumicino Airport in Rome, Italy Reuters In pictures: President Donald Trump on tour 24 May 2017 US President Donald Trump and First Lady Melania Trump wave to reporters before boarding the Air Force One to Brussels, at the end of a 2-day visit to Italy including a meeting with Pope Francis at the Vatican, at Rome's Fiumicino international airport AP

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.