OTTAWA -- Prime Minister Justin Trudeau leaves today for Brussels for the NATO leaders' summit, the alliance's first such meeting since U.S. President Donald Trump moved into the White House.

The future of military alliances, the fight against climate change and even free trade are all expected to be on the agenda as Trump sits down with his NATO and G7 counterparts.

But officials and experts expect the spotlight to shine brightly on the fight against terrorism after the suicide-bomb attack at a music concert in Manchester, England on Monday, which killed 22 people and injured 59.

Much of the emphasis at the NATO summit in Brussels is also expected to be on the amount allies spend on defence.

Canada spends only about one per cent of GDP, which is half of NATO's stated target, and puts the country among the bottom third of allies.

Following Brussels, Trudeau will jet to Taormina, Italy, for this year's G7 gathering, before ending his foreign tour with a stop in Rome to meet Italian Prime Minister Paolo Gentiloni and the Pope.