Security is shifting from yesterday’s weapons — aircraft carriers, nukes and superjets — toward tomorrow’s — cyber and information. The new strategic question: “Who can paralyze whom?” Washington still arms for yesterday’s wars, leaving us unprepared for the next war that may sneak up on us because initially it doesn’t even look like war.

Technology changes security concerns. In 1453, Ottoman cannons cracked Constantinople’s walls, and quickly all Europe’s monarchs acquired them. Gunpowder brought new fortifications, standing armies, taxes and royal absolutism.

In the 19th century, railroads and telegraphy brought mobility and rapid mobilization. Barbed wire and machine guns stalled warfare in trenches. Navies prized supposedly invulnerable battleships until Pearl Harbor; then aircraft carriers became the great weapon. Are they still? Or are these floating steel cities sitting ducks for China’s anti-ship missiles, now called “carrier-killers”? We send smaller ships through the Taiwan Straits but keep our carriers far off China’s coast.

Nuclear weapons turn out to be almost perfectly unusable. Fear of retaliation has produced a fairly stable deterrence balance. The closest it came to catastrophe was the 1962 Cuban missile crisis, although some argue that the 1961 Berlin Wall crisis was more dangerous. At Checkpoint Charlie, a tank gunner could have sent a shell down Friedrichstrasse, starting an escalation. Israel-Iran hostility may produce the first use of nukes since Nagasaki.

We might consider the unusability problem before making major expenditures to modernize our nuclear arsenal. In the 1950s, Washington accepted a “finite deterrence” theory, that you needed only a few hundred warheads to dissuade an attacker. In 1960, Herman Kahn argued the Soviets could overwhelm our finite deterrence, so our nukes had to outnumber theirs. Result: Both sides relentlessly added thousands of useless warheads, bringing nervous trigger fingers and worse security.

While America and Russia still compete in nukes, China, with perhaps 300 warheads, practices finite deterrence. North Korea, with estimated fissile material for 45 warheads, still follows the more-is-better theory that devours their GDP even as mass hunger returns. Pyongyang and Tehran seem unable to grasp that nukes may provoke more than they deter.

Superjets ill suited our wars in Afghanistan and Iraq. They’re too fast to hit crouching jihadists with AK47s. Old, slow A-10 Warthogs, on the other hand, hit battlefield targets and saved our butts several times. The F-35, so super-complex that none matches it, costs several times its original estimate and is frequently grounded.

Are tanks still the great weapons of ground warfare? Our Javelin shoulder-fired missile knocks them out with near-certainty. We have dozens of Javelins in Ukraine, none fired so far, but useful in making the Russians hesitate before pushing westward. If the Russians have anything similar, we’d better pause too.

As Defense Secretary Lloyd Austin worries, We must prepare to prevent the next war, not the previous.

We have trouble taking cyberattacks seriously. Russian troll farms goad us into hating each other. Granted, we do a pretty good job on our own. Chinese industrial espionage steals scientific secrets online. We can’t even fight cybercriminals. Last week their “ransomware” shut down a major fuel pipeline.

A serious cyberattack could paralyze our power grid, aircraft flights, information technology and financial markets. Major powers are constrained from launching such attacks for fear of retaliation. The unstated message: You mess with our cybernetworks and we’ll fry yours! Like nuclear deterrence, this has prevented all-out attacks but not little nibbling incursions.

Transnational terrorists, however, without countries to defend, feel no constraint from launching cyberstrikes on any vulnerable part of our networks. Like 9/11, we can’t envision it until it hits. Are we technically and psychologically prepared to handle major cyberattacks?

How dependent are we on earth-orbiting satellites for navigation and data transmission? Very. How hard would it be to either knock out these satellites or jam them? Not very.

Drug overdoses killed over 81,000 Americans last year, most of them from added fentanyl, cheaper than prescription painkillers and heroin and much stronger. Most fentanyl comes from China, often mailed in small packets. Why can’t we block this nefarious trade? What would we say if an endless war cost tens of thousands of American lives a year?

We envision war as blasted battlefields and cities. But warfare can also be waged more subtly by confusion and demoralization, as Sun Tzu wrote 2.5 millennia ago. The next war will end not with surrender ceremonies but with one power withdrawing from major international roles while other powers expand their influence. That’s what we did after a demoralized Soviet Union collapsed from self-inflicted internal problems. China’s clever “grey-zone strategy” in the China Seas — expansionist but veiled — leaves us unable to clearly define our national interest. We better define it soon.

We still need robust conventional defenses, especially the ability to put boots on the ground. But we also must guard against the less-conventional threats that come with modern technology.