Canadian Prime Minister Justin Trudeau met EU leaders in Brussels on Sunday to finally sign a giant trade deal seven years in the making that was almost torpedoed by a small region of Belgium.
The ceremony had been pushed back from Thursday after French-speaking Wallonia, with just 3.6 million people, initially vetoed a deal affecting more than 500 million Europeans and 35 million Canadians.
Protesters on Sunday threw red paint at the European Union's headquarters, banged drums and chanted slogans as Trudeau arrived to meet EU President Donald Tusk and European Commission chief Jean-Claude Juncker.
"Well done, well done," Trudeau said as he hugged and kissed Tusk and Juncker on his arrival amid tight security. "Things were difficult but we managed to succeed in the end."
"What patience," replied Juncker, adding: "This is an important day for the EU and for Canada too because we are setting an international standard that will have to be followed by others."
The start of Sunday's summit was further delayed when Trudeau's plane was briefly forced to turn back due to mechanical problems, capping two weeks of haos over what was meant to be a symbolic sign-off.
Formally known as the Comprehensive Economic and Trade Agreement (CETA), the deal removes 99 percent of customs duties between the two sides, linking the single EU market with the world's 10th largest economy.
The Belgian drama had sparked dire warnings for the EU's credibility as a trading partner as it wrestles with Britain's shock vote to leave, a huge migration crisis and the threat of a resurgent Russia.
After years of negotiations the deal almost collapsed, with Trudeau only agreeing late Friday to fly to Brussels after Wallonia finally agreed to join the rest of Belgium and the other 27 EU member states in approving the deal.
The pact required all EU member states to endorse it and in some cases such as Belgium's for regional governments to agree too, giving tiny Wallonia an effective veto.
The Walloons had for two weeks resisted huge pressure from all sides until it won concessions for regional farming interests and guarantees that international investors will not be able to force governments to change laws.
The concerns in the declining industrialised region in Belgium's south reflected wider concerns in Europe about globalisation, as well as fears among activists that such deals erode consumer, social and environmental protections.
Belgian Foreign Minister Didier Reynders said "nothing is simple in Belgium but few things are impossible" as he officially signed up to the deal on Saturday.
Belgian Prime Minister Charles Michel insisted that the marathon talks with Wallonia "did not change a comma" in the deal. But Walloon government head Paul
Magnette said he received assurances from the federal government of strengthened social and environmental protections.
The EU-Canada deal has also drawn widespread protests from anti-globalisation "Stop CETA" activists who say it undermines local industries and standards for healthcare and other issues.
On Sunday around 100 protesters banged drums and shouted slogans outside the European Council building while Belgian riot police backed by water cannon looked on, AFP reporters said.
The glass front doors of the building were also daubed with red paint after some protesters briefly managed to break through police lines.
The activists also see CETA as a Trojan horse for an even bigger and more controversial deal between the EU and the United States.
Negotiations for that deal, known as the Transatlantic Trade and Investment Partnership (TTIP), have however stalled in recent weeks with the goal of approving it by the end of President Barack Obama's term of office now having been abandoned.
The troubles with the Canadian deal have meanwhile been seen as a possible harbinger of things to come for Britain as it tries to negotiate a new trade pact with the EU after it leaves the bloc -- most likely in 2019. (AFP)