The Obama administration has tried to spin its timidity and ineptitude in the face of Islamist terrorism as a clever policy of “strategic patience.” With eyes closed and fingers crossed, the president hoped that, miraculously, the mortal threat from ISIS would wither away.

You might as well hope that malignant tumors will cure themselves.

President Obama’s approach of delayed and diluted action — ever doing the minimum demanded by domestic politics — has allowed ISIS not only to survive but to expand its appeal, its numbers, its territory and its global impact. Starbucks took 30 years to reach five continents. ISIS did it in two.

In his press conference in Turkey on Monday, Obama continued to insist that there was no need to change his Syria policy, that success merely “will take time.” Yet it’s precisely because of our unwillingness to take the threat seriously and then to respond forcefully that ISIS now has a deep bench of seasoned “middle managers” ready to replace the leaders we kill; it has tens of thousands of combat-veteran jihadis; it’s made the caliphate real in the city of Raqqa; and it’s had the leisure to learn how to cope with our weapons (human shields work every time).

With a free assist from Edward Snowden, it’s even learned how to circumvent our intelligence efforts. Ask the French.

Obama wouldn’t go to Raqqa. So the jihadis went to Paris.

Friday’s thoroughly planned and boldly executed attacks not only brought darkness to the City of Light, but scored an enormous propaganda victory for ISIS. With almost 500 Western casualties, a quarter of them dead, the carnage will prove electrifying to potential jihadi recruits around the world.

Just as important, our dithering also gave ISIS time to refine its techniques and strategies. Less than a year ago in Paris, a struggling al Qaeda staged a shocking, if crude, attack on the offices of Charlie Hebdo, the satirical magazine. That incident now seems bush league compared to the latest attack, with its near-simultaneous strikes on six symbolic “lifestyle” targets packed with infidel victims.

The first attack was savage. Friday’s attack was savage and sophisticated.

Last week’s attack was planned in Syria. Three strike teams then infiltrated back into France or were activated in place. A support network supplied them with weapons and cars.

Limiting their communications to the bare minimum (and encrypting them), they relied largely on the techniques terrorists used a century ago: small cells, minimal contact, low profiles and deep planning (real strategic patience).

The result? A handful of men with small arms and home-brew explosives stunned the world.

Technically, the Paris attacks were the result of intelligence failure. But that label’s just too easy. The French are quite good at surveillance. But they’re restricted by law (as are we) in what they can do domestically; they’re overwhelmed by the number of potential threats; and they face an adaptive, elusive enemy.

The ugly truth is that ISIS and its affiliates have been allowed to put down such deep roots that more attacks are inevitable. Here, too.

What can be done? The answer is easy to mouth — and unwelcome to those who conduct foreign policy by platitudes (such as “there’s no military solution”). The base line is that you can’t win by playing defense. You must take the war to the enemy — without restraint. If you’re not determined to win at any cost, you’ll lose.

Our military has the resources to shatter ISIS, but political correctness has penetrated so deep into the Pentagon that, even should a president issue the one-word order, “Win!,” our initial actions would be cautious and halting. We’ve bred a generation of military leaders afraid of being prosecuted by their own government for the kind of errors inevitable in wartime. Instead of “leaning forward in the foxhole,” our leaders lean on lawyers.

If lawyers had had to approve our World War II target lists, we couldn’t have won. War is never clean or easy, and the strictures imposed on our military today just protect our enemies. Collateral damage and civilian casualties are part of combat and always will be. The most humane approach is to pile on fast and win decisively — which results in far less suffering than the sort of protracted agony we see in Syria.

The generals who won World War II would start by leveling Raqqa, the ISIS caliphate’s capital. Civilians would die, but those remaining in Raqqa have embraced ISIS, as Germans did Hitler. The jihadis must be crushed. Start with their “Berlin.”

Kill ten thousand, save a million.

Unthinkable? Fine. We lose.

And the jihadis? They’ll always have Paris.

Ralph Peters is Fox News strategic analyst and a retired Army officer.