Maybe it’s fitting that a winter storm warning delayed Tuesday’s scheduled meeting between President Trump and German Chancellor Angela Merkel. After all, a chill characterizes the relationship between Berlin and Washington after Trump’s unexpected election.

The distance is mostly due to Trump’s undisciplined, unwise tweets and blurts, as when, in a pique over not being named Time magazine’s 2015 “person of the year,” Trump tweeted that the winner, Merkel, was “ruining Germany.” Or when he called himself “Mr. Brexit,” suggesting his glee over the British decision to exit the political entity championed by the chancellor and other European allies unsure of the U.S. commitment to European political unity and collective defense.

Along with many other reality checks, Trump should have discovered by now that a united Europe is in America’s best interest and that Brexit, like other movements toward nationalism, undermines the cohesion undergirding Western security and prosperity.

For her part, Merkel’s statement after Trump’s win, in which she called on the U.S. and Germany to work together to further mutual values of “democracy, freedom, respect for the law and for human dignity, regardless of origin, skin color, religion, gender, sexual orientation or political inclination,” seemed more complaint than compliment. In Washington, Merkel will try to establish a constructive relationship while staying stalwart in defense of European values, a balancing act all the more challenging in the context of Merkel’s tight re-election race back home.

But balance she must. And Trump should, too. Sure, this is not the U.S.-U.K. “special relationship,” but Merkel is the continent’s most consequential leader, and transatlantic cohesion is needed even if Trump is pushing an “America first” foreign policy.

The leaders should strive to find common ground on fundamental issues. On NATO, Trump could once again reiterate unequivocal support for the alliance, as he wisely did in his address to a joint session of Congress. Even more meaningful would be U.S.-German unity on upholding sanctions on Russia for its cleaving of Crimea and destabilization of Eastern Ukraine. Trump should confirm the U.S. commitment to the Paris climate change agreement, too. And Trump’s blunt rejection of multilateral trade pacts makes even less sense regarding the previously proposed U.S.-E.U. Transatlantic Trade and Investment Pact, particularly considering the shared values each side espouses.

Citing security “which the U.S. underpins,” an open Europe “which Germany underpins,” a continent “not dominated by any power or groups of power” hostile to the U.S., and a partner — Europe, with Germany as its dedicated center — essential to U.S. interests, Daniel Hamilton, executive director of the Center for Transatlantic Relations at the School for Advanced International Studies at Johns Hopkins University, told an editorial writer that “if we don’t agree across the Atlantic nothing gets done in the world and Germany holds all of that together.”