Lost in the hubbub over Who Knew What When (then changed it) about the Sept. 11 terror attack on our Benghazi consulate is one huge question: When do the terrorists pay for what they did?

We lost four brave Americans at the hands of a pro-al Qaeda group, Ansar al Sharia, and other extremists. In October, President Obama vowed to “hunt down the attackers.”

Of course, we need to know what happened prior to the tragedy so we can prevent something like this from happening again. For example: Was there an intelligence failure that kept us from having advanced warning?

Plus: Why didn’t we have enough security at the Benghazi consulate despite numerous requests from the staff in the field for more protection? And why wasn’t US military assistance rendered during the attack?

We also have to know why Team Obama so badly bungled how they told us initially what happened, including why UN ambassador Susan Rice said what she said on those Sunday morning new shows.

(You remember: Rather than Benghazi being a terror attack, it was a copy-cat demonstration of the one in Cairo, which arose in response to an anti-Muslim video produced in the United States.)

These questions, and others, are important — and Congress needs to get to the bottom of it all.

But when will the terrorists who murdered Americans, including our ambassador, get their due?

From the outside, after nearly three months, it doesn’t appear much is happening to bring the terrorists to justice.

Yes, the Libyans rounded up a few of the “usual suspects” in the days after the attack, but little more seems to be going on to get as many as 100 terrorists involved in the raid. (A Miami Herald report claims that the Libyans have actually arrested no one.)

Some feel the Libyan government is dragging its feet for fear of making enemies of the myriad powerful, well-armed extremist militias — which, more than a year after the revolution ended, still operate freely across the country.

Indeed, the person many believe responsible for the assault, Ahmed Abu Khattala, the leader of a wing of Ansar al Sharia, is still reportedly walking the streets of Benghazi. (He’s denied involvement in the attack.)

Equally troubling, a Time report indicates that terrorist sympathizers or collaborators among Libya’s law-enforcement and security services might be implicated in the attack.

OK, so the Libyans are basically paralyzed, but what are we doing?

Well, the FBI is investigating the case after a very late start. The State Department is also doing a report, and it’sgenerally assumed that US intelligence is gathering information that will pinpoint the attackers.

Of course, before a US special- forces raid or a drone strike is conducted against those who did this, we’ll need good intel to make sure we get the right people at a propitious time and place.

But as the old adage goes, punishment should be not only just, it should be swift. Yet “swift” is clearly no longer an option after nearly three months.

Our seeming inactivity and silence send a message to the terrorist world — loud and clear: We’re not only inept, we’re weak.

It’d be nice to think we’re lulling the bad guys into a false sense of security before we act, catching them off guard. But, for the moment, we may also be giving them the sense that they have license to kill Americans with impunity.

Thankfully, if there’s one thing terrorists understand — and respect — it’s strength. Now would be a good time to show some, by bringing the Benghazi terrorists to account.

Peter Brookes is a Heritage senior fellow and a former deputy assistant secretary of defense.