This year is shaping up as an inflection point for Europe.

Key national elections and European Union parliamentary elections could recast the continent’s political discourse for years to come. Britain is set to leave the European Union at the end of March, and NATO will mark its 70th anniversary as it, fittingly, continues to return to its roots: a focus on collective defense.

All of this affords the U.S. an important opportunity to affect the trajectory of Europe by acting swiftly to secure a free trade deal with the United Kingdom, stop Germany’s Nord Stream 2 oil pipeline to Russia and consider a permanent military presence in Poland and the Baltic states.

Furthermore, Washington would be wise to remain actively engaged in the Balkans, the Black Sea and Ukraine — three key regions where Russian actions increasingly threaten European security.

There is much unfinished business in the Western Balkans. Ethnic, religious and cultural differences, fueled by historical grievances, still have the potential to set off renewed hostilities and violence. Furthermore, the challenges posed by Russia’s destabilizing influence, rising Chinese interest and investment in the region, pockets of Islamist extremism, high unemployment, and lack of economic opportunity threaten to ensnare the Balkans in permanent geopolitical quicksand.

The Trump administration cannot afford to take its eye off the ball in the Balkans. Rather, it should work to expedite Macedonia’s accession to NATO, extend visa waiver privileges to Croatia and prevent a land swap agreement between Kosovo and Serbia.