Here’s a sobering thought to contemplate on this New Year’s Day: Will we be able to recognize the next Pearl Harbor-style attack against America before it’s too late to defend ourselves?

This is not just a random question. And it’s not being asked just to frighten you.

Nearly a generation has passed since Islamic extremists crashed jetliners into the World Trade Center. Nobody saw that attack coming. And be sure of this: the next attack will not bear any resemblance to 9-11.

On Wednesday, James Mattis left the office of U.S. Secretary of State. The former U.S. Marine general submitted his resignation over foreign policy disagreements with President Donald Trump. The presumed catalyst was Trump’s order of a full troop withdrawal from Syria.

The withdrawal, Trump says, indicates the final and complete destruction of the forces behind the World Trade Center and related attacks — forces that shape-shifted occasionally into al Qaeda, ISIS, the Islamic State and various splinter groups in various rogue countries.

The 9-11 chapter is essentially over.

Enter a new chapter to be written by a new kind of defense secretary.

Enter Patrick Shanahan, 56. He is not a warrior. He’s a scientist. The Washington state native holds master’s degrees in mechanical engineering and business administration, both from the Massachusetts Institute of Technology. For more than 30 years, Shanahan has been a whiz kid at Boeing Corp., where he’s known affectionately as “Mister Fixit.” He has extensive experience developing commercial products (airliners and helicopters) as well as military ones (missiles).

When Trump appointed Shanahan as Mattis’ successor, he obviously had in mind his recently declared launch of a United States Space Force.

Are concepts envisioned (and maybe bluffed) during Ronald Reagan’s “Star Wars” program 30 years ago being deployed now? Possibly. At least four random unexplained events have been reported in recent days, most recently on Dec. 27 in New York City and Kenner, Louisiana, where the electric utilities blamed transformer explosions for turning the night sky a bright cobalt blue.

Hmm. We don’t recall this phenomenon happening anywhere previously, but twice on the same night, in cities 1,300 miles apart? Interesting coincidence.

On Nov. 28, the National Geographic reported the detection of rhythmic seismic ripples going around the world. “The seismic waves began roughly 15 miles off the shores of Mayotte, a French island sandwiched between Africa and the northern tip of Madagascar. The waves buzzed across Africa, ringing sensors in Zambia, Kenya, and Ethiopia. They traversed vast oceans, humming across Chile, New Zealand, Canada, and even Hawaii nearly 11,000 miles away,” NatGeo reported. “These waves didn’t just zip by; they rang for more than 20 minutes. And yet, it seems, no human felt them.”

Shanahan will command a $700 billion annual Pentagon budget, the federal government’s largest, with 2.8 million military and civilian employees. That’s a massive bureaucratic machine that has cutting edge technology and research at its disposal.

It has stealth technology. It has megadata collection capabilities, artificial intelligence, nuclear submarines and aircraft carriers. It has Navy SEAL Team 6. It has heaven knows what else.

Meanwhile, we remain doggedly focused on a wall proposed for the U.S.-Mexico border.