President Donald Trump arrived in Brussels this morning to meet with main European leaders and other members of NATO military alliance.

After visiting Saudi Arabia, Israel and Palestine, and the Vatican, Trump will focus the last part of his first official trip abroad on discussing peace and security matters with his European allies in a series of talks described as “tough” by his team, as reported in the BBC.

During his first five months in power, the US president has been especially critical with the real role of NATO to fight terrorism and with the future of the military alliance if members don’t contribute enough money on defense.

Before the meetings in Brussels began, US Secretary of State Rex Tillerson told reporters that Mr Trump "really wants to persuade NATO members to step up and fully meet their obligations".

Trump wants NATO members to accept his request to join a US-led coalition to fight the Islamic State, ISIS. The terrorist band has claimed responsibility for the suicide terrorist attack that killed 22 at a Pop concert in Manchester three days ago. 

British prime minister Margaret May is also in Brussels, where she is expected to push NATO to join the global coalition against Islamic State.

After the NATO gathering in Brussels, Trump will be leading to the G7 meeting in Sicily.

While Trump hold meetings with European Leaders, the streets of Brussels, a city he once described as a “hellhole”, filled with thousands of protesters showing angst over his visit.

"If you don't want Trump in Belgium clap your hands," chanted some, as reported by CNBC. "Hey hey, ho ho, Donald Trump has got to go,” others shouted. Among the protesters, some banners criticized the lack of US commitment to fight climate change.

Before delivering a speech at the NATO headquarters in Brussels, Trump is scheduled to have a private lunch with new French President Emmanuel Macron. “Mr Macron is expected to try to persuade Mr Trump not to renege on the Paris climate accord,” as reported in the BBC.