BRUSSELS — Jean Monnet, one of the founders of the European Union, wrote in his memoirs that “Europe will be forged in crises and will be the sum of the solutions adopted for those crises.”

The war in Ukraine is only the latest crisis to confound Europe and rip away its illusions. A return to full-scale territorial warfare rarely seen in Europe since World War II has altered the European Union and NATO, both their present and their future, with consequences still unclear.

Along with China, Europe’s crises will be the undercurrent jolting discussions at the World Economic Forum, which opened on Monday in Davos, Switzerland. Its theme of “Cooperation in a Fragmented World” summarizes the aspiration driving some of the policies rapidly adopted on the continent since Russia’s invasion of Ukraine last February.

Both the European Union and NATO have responded well and remain united, at least on the surface, to challenges including war, economic stress, energy disruption and humanitarian crises — all topics on the Davos agenda.