LONDON — President Trump has given a master class in the unhappy link between his “gut” and the gutting of American credibility. His flippancy over the fate of the Kurds in northern Syria has been criminal in its disregard for human life, America’s friends and American interests. From Trump’s sort-of green light to Turkey’s assault on northern Syria, to his threat to “totally destroy and obliterate” the Turkish economy, to his Chamberlain-like dismissal of Kurds’ fate (“We are 7,000 miles away!”), he has played the clown in chief.

America’s word is worth less today than at any time since 1945. Trust is not an easily recoverable commodity. Solemn accords entered into by the United States, like the Iran nuclear deal, are ripped up — and replaced by empty threats. Friends like the Kurds who have shed blood to inflict great harm on the Islamic State are betrayed. Day after day a president for whom facts don’t matter dismantles the idea of truth.

The postwar American-led order was based on treaty undertakings convincing to allies. That’s dead. What will take its place is unclear. Under President Trump “foreign policy” has become an oxymoron . Foreign theater has replaced it — and people die on the bloody stage of Trump’s whims.

Europeans now shrug when they don’t laugh. The consensus is the United States has lost it. There’s nobody home. A child-president in the Oval Office writes a letter to the Turkish leader who appropriately tosses it in the garbage. That’s where we are this week. Next week is anybody’s guess. Trump and uncertainty are synonymous. A rough compass indicates presidential derangement is pointing north.