In January, Joe Biden will take charge of an executive branch left in woeful disrepair. Practically every important federal institution has been scorched by four years of sustained assault by his predecessor — none more so than the State Department.

President Donald Trump has damaged American diplomacy in word and deed. His secretaries of state, first Rex Tillerson and then Mike Pompeo, have damaged the department deeply. Their open hostility toward career foreign affairs professionals has led to an exodus of talent, leaving important roles either unfilled or, worse, manned by unqualified political appointees.

As a result, morale in the department has plummeted, as has its prestige abroad. The Colombian ambassador to Washington was caught on tape last year lamenting that "The U.S. State Department, which used to be important, is destroyed, it doesn't exist." He might've been speaking for America's allies and enemies alike.

Trump has also accelerated the trend, already conspicuous during President Barack Obama's administration, of conducting foreign policy from the White House. His tendency to base foreign relations on his personal ones has often left diplomats with the impossible task of squaring the president's fondness for strongmen — Vladimir Putin, Recep Tayyip Erdogan, Jair Bolsonaro and Kim Jong Un spring immediately to mind — with the circle of America's interests.

All this is now Biden's to fix. The president-elect must also conquer his own proclivity for personalizing foreign affairs. As a longtime member of Washington's foreign policy establishment — both as a senator and as Obama's vice president — he has more than a passing familiarity with many world leaders, and often cites old friendships when asked how he might deal with difficult diplomatic challenges.

America would be better served by returning foreign relations to the realm of institutions rather than individuals.

Biden's campaign promises to "build back better" were directed to the economy, but he has an opportunity to apply the credo to American diplomacy. He shouldn't waste it.

FROM AN EDITORIAL IN BLOOMBERG OPINION