It seems like only yesterday that libertarians of both the left and right were in full-throated outcry about the supposed “militarization” of the police and the supposed excesses of the “surveillance state.” Those arguments don’t look so hot in the wake of the terrible attack in Paris which showed the dangers of (a) not having police who are adequately armed, trained, and ready to stop terrorists with AK-47s and suicide vests and (b) not having adequate surveillance of terrorist networks to stop their attacks before they occur.

It is the second weakness — the inability to adequately monitor terrorist networks — that has understandably gotten the most attention. James Comey, the FBI director, has warned that the spread of encrypted communications is making it impossible for authorities to intercept terrorist messages even when they have a court order to do so.

The Manhattan district attorney Cyrus Vance Jr. joined Comey in a press conference where he “released a 42-page white paper arguing that his office was unable to execute 111 search warrants for smartphones from September 2014 to October 2015 because the devices employed Apple’s ‘full disk encryption.’ That technology prohibits anyone, except the iPhone’s owner, from accessing a device’s contents without a user’s password.”

William Bratton, the New York police commissioner, also joined those criticisms, warning, “We have, in many respects, gone blind.”

And CIA Director John Brennan got into the act, too, warning that “in the past several years because of a number of unauthorized disclosures and a lot of handwringing over the government’s role in the effort to try to uncover these terrorists, there have been some policy and legal, and other actions that are taken that make our ability collectively internationally to find these terrorists much more challenging.”

Reports that the Paris attackers communicated with encrypted apps underlines the danger and shows that Messrs. Comey, Bratton, and Brennan are not scare-mongering — they are warning the public of very real dangers that need to be urgently addressed.

Yet the Obama administration abandoned efforts to pass legislation that would mandate companies such as Apple, Google, and Microsoft maintain a “back door” that would allow law enforcement to access communications when lawfully entitled do so. This mandate was unpopular with technology companies and their libertarian allies who conjured up fears of Big Brother, warned that poor Internet security could be exploited by hackers, and fretted that if American companies installed “back doors” users would migrate to foreign firms that didn’t. These are reasonable worries, but the Paris assault (in addition to other recent attacks, such as the bombing of a Russian civilian airliner) should tilt the balance in favor of more law enforcement capability, not less.

Not only did Obama refuse to stand up to the technologists and libertarians on this issue, but he also gave up the fight on the NSA’s collection of metadata, which was unfairly demonized after it was revealed by the traitor Edward Snowden. This simply refers to the NSA practice of collecting phone records listing connections between numbers (but not the content of calls) in order to map terrorist networks. That authority, which was repealed with the support of a bipartisan coalition in Congress (including the likes of Ted Cruz and Rand Paul), will now expire at the end of this month, leaving us a bit more vulnerable to attack at a time when ISIS is more dangerous than ever.

Those decisions, which seemed reasonable to many just a few weeks ago, need to be reexamined in light of the Paris attacks which make clear that terrorism is not a remote or outlandish possibility — it is a major threat, and American cities are just as vulnerable as Paris was.

The Paris attack should also make us rethink the outcry over police departments getting military-style equipment. The ACLU is alarmed: “The images on the news of police wearing helmets and masks, toting assault rifles, and riding in mine-resistant armored vehicles are not isolated incidents — they represent a nationwide trend of police militarization.” Why, the civil libertarians demand to know, are police stockpiling helmets, assault rifles, armored vehicles? Isn’t that overkill?

Actually, no. The Paris attack shows that such military-style equipment is necessary to respond to well-armed and well-organized terrorist attacks. That is why the New York Police Department is creating a new counter-terrorism unit — soon to be more than 500 strong — that will be armed with assault-rifles, not just standard pistols. It’s unfortunate that such measures are necessary. It would be nice if we could go back to the days when all we needed were patrolmen walking a beat with a billy club. Officers on patrol are still necessary, but so are SWAT teams ready to do battle with terrorists who exist in the real world, not just in the imaginations of Hollywood screenwriters.

That is not a defense of police misconduct, which is a real problem that needs to be addressed. But we should not lose sight of the bigger picture that we need the “thin blue line” — backed by robust surveillance capabilities — to protect us against those who think they have a mandate from Allah to commit mass murder.