Denmark launched its presidency of the European Union on Thursday with a call for Europe to unite to take on war in Ukraine and chaos caused by U.S. President Donald Trump's global tariff hike which are likely to mark the Nordic country's six-month term at the helm of the world's biggest trading bloc.

If the United States were to not give Ukraine the military support it needs, it would be a serious setback for Ukraine, the EU and NATO, Denmark's Prime Minister Mette Frederiksen said on Thursday.

Denmark has taken over the six-month rotating presidency of the Council of the European Union as questions swirl over Europe's security and trade and a war still raging on its eastern flank.