President Trump has yet to decide on his security and military advisers’ proposal to send at least 3,000 more US troops to Afghanistan. Wednesday’s massive terrorist bombing in the heart of Kabul is a powerful argument for giving the go-ahead.

At least 90 people were killed and 450 injured when a tanker truck packed with explosives blew up in the Afghan capital’s diplomatic quarter.

No one wants to see America bogged down again in Afghanistan — least of all Trump, who campaigned hard against US nation-building.

But this commitment would mean avoiding the mistakes of the past — especially those of President Barack Obama, whose hasty withdrawals from Afghanistan and Iraq ended in the resurgence of the Taliban and the rise of ISIS.

The defeat of ISIS in Iraq and Syria is well in hand, but the Taliban and other Islamist groups control or contest one-third of Afghanistan. Moving to stabilize and support President Ashraf Ghani’s beleaguered government is not nation-building. It’s about fighting terrorism and preventing the “losers” from gaining a new safe haven from which to unleash havoc on the West as well as the Middle East.

If Trump moves ahead, he would do so by linking a strengthened US troop presence with clear conditions on the battlefield — not the arbitrary deadlines set by Obama.

Clearly, Trump understands the political risks and pitfalls of re-engaging. When it comes to Afghanistan, most Americans want to be over and done with it.

But reality keeps intruding, and Trump’s reality is that he can’t ignore the mess left him by Obama.

Whatever the financial price of standing up, raising the white flag to terrorism would cost far more in innocent lives lost.