In trying to end the Afghan war with a Camp David summit, President Trump was making good on his campaign promises as well as aiming to deliver the US pullout Americans overwhelmingly desire.

But he was true to his oath of office, and to his vows not to be a sucker, in canceling.

As the president rightly noted, the Taliban showed its true colors by taking responsibility for Thursday’s suicide attack in Kabul, which killed 10, including one US service member. That proved that the supposed agreement in principle reached by US envoy Zalmay Khalilzad wasn’t really an agreement at all: The Taliban was just trying to collect whatever concessions it could get.

All this should dispel the idiotic idea that the West’s mission in Afghanistan is any kind of imperialism: It’s a concerted, painstaking effort by diplomats and soldiers who desperately want an end to the war — an honorable end.

The deal would have reduced US troops in Afghanistan from 14,000 to 8,000 over the next five months, with other NATO forces likewise dropping. With the Taliban now issuing fresh threats, that has to be off the table — indeed, Trump should at least consider upping the US presence.

America’s enemies and rivals should know by now that, even when this president would very much like a deal, he’s not going to take a bad one. Too bad the Taliban, at least, needs another lesson.