Ever since our lopsided victory in the Gulf War in early 1991, the U.S. military has been venerated by many Americans as an unbeatable force. How rapidly our combined air-ground offensive crushed Saddam’s large yet ponderous army gave the Pentagon an aura of invincibility. Military leaders and defense thinkers proclaimed the dawn of new era in warfare. With our advanced technology and precision strikes, everything was different.

But was it? In hindsight, the Gulf War merely confirmed what military historians always knew, namely that better weaponry and command-and-control habitually crush large numbers of less well-equipped enemies. A generation on, the “lessons” of 1991 appear no more noteworthy than the “lessons” of Omdurman in Sudan in 1898, when two brigades of British regulars easily crushed a force of 50,000 jihad-fueled natives because, as the wags of the day put it, “We have got the Maxim Gun, and they have not.”

Yet since the Gulf War, the U.S. Army’s technological edge over its potential foes— what defense doyens term overmatch—has dwindled, slowly but irrevocably. Through the decade after 1991, the army was busy managing post-Cold War cutbacks and peacekeeping in the Balkans and saw no peer-competitors anywhere. Since 9/11, as plausible rivals like Russia and China have slowly come into focus, our army has been busy managing costly and ultimately futile campaigns in the Greater Middle East. Our diffident war in Afghanistan, America’s longest by a good margin, is in its 17th year, and strategic victory is now as far off as it has ever been there.

That American strategy-making is flawed is now painfully evident, but until recently the tactical success of our military seemed at least like a safe assumption. It does no more. A generation of down-punching against third-rate insurgents in Afghanistan and Iraq has proved to be poor preparation for combat against enemies who can seriously contest the modern battlefield.

Russia’s military performance in Ukraine since 2014, where the Kremlin’s undeclared war continues on low boil, has proven to be a particular eye-opener for the U.S. Army. In eastern Ukraine, Russian ground forces have demonstrated impressive acumen in electronic warfare, where their ability to rapidly geolocate Ukrainian forces by tracking their communications—including the careless use of mobile phones in the combat zone—has led to the deaths of many Ukrainian troops.

However, our weakness in EW, as the Pentagon terms it, does not surprise. Even in the 1980s, Soviet expertise in what they tellingly term radio-electronic combat outpaced the U.S. Army’s, while our perennial communications indiscipline, which cost many American lives in Vietnam, shows no signs of going away either. Our army is now trying frantically to catch up with the Russians in EW, but we’re behind a full generation, and achieving parity in the vitally important battle in the ether will prove expensive and time consuming.

Genuinely shocking, though, is how far ahead the Russians have gotten in artillery. That arm is the great killer on the modern battlefield, for over a century now, and Russian gunnery has always been impressive. Their artillery was fearsome in the time of the tsars (“The Irish fight well, but the Russian artillery’s hotter than Hell,” as a popular ditty had it during the Crimean War), and so it has remained. Stalin referred to his guns as “the God of War” and it’s no exaggeration to state that the Red Army in 1944-45 blasted its way clear to Berlin with its massive artillery corps.

But the U.S. Army’s gunnery was no less impressive. Our artillery was the guarantor of victory in the Second World War on all battlefronts. Contrary to Hollywood myth making, the U.S. Army had serious defects in the fight against the Wehrmacht. Outside a few elite units, our infantry was subpar, while our tanks were death traps compared to German models. Our gunnery, however, was world class, and the U.S. Army’s field artillery outpaced Hitler’s gunners in precision and weight of shell. For all his bluster about tanks, General George S. Patton spoke the truth when he stated, “I do not have to tell you who won the war. You know our artillery did.”

It was the same for decades after. In Korea and Vietnam, our field artillery saved the day—and countless lives—time and again, allowing outnumbered American infantry to prevail in battle, while the U.S. Army’s prowess in precise, long-range gunnery crushed Saddam’s army in the Gulf War just the same. That vital overmatch has evaporated since 1991.

In the generation since the Cold War ended, the Russian military has maintained its traditional competence in gunnery, fielding new classes of field artillery, both guns and missiles, while the U.S. Army has stagnated. A brief look at the current situation reveals the extent of the problem. Russian maneuver brigades possess a regiment’s worth of artillery, two battalions of self-propelled 152 mm howitzers plus a battalion of rocket-launchers, 54 artillery pieces in all. In contrast, our heavy brigades possess just a single battalion of no more than 24 155 mm self-propelled howitzers (and in Stryker brigades the howitzers are towed, not self-propelled).

The situation repeats above the brigade level, with the Russians having more artillery pieces and, worse, they customarily outrange American models by a good margin, sometimes twice as much. In terms of range and weight of shell, the Russians today possess alarming advantages over the U.S. Army. Only in target acquisition do we seem to be at an advantage, thanks to drones and better tactical intelligence, but that edge, too, is slipping. Having grown accustomed to drones overhead nonstop, against enemies who cannot shoot them down, the U.S. Army may be in for a rude awakening in a contested fight.

Worst of all, the field artillery branch’s crisis has been building for 15 years, as deployments of gunners as infantry in the Middle East have eroded skills. Not only have new weapons not been acquired, basic gunnery acumen has atrophied among officers and NCOs. A full decade ago, artillery officers were sending up warning flares, with some terming theirs a “dead branch walking.” Nobody took action, so the army’s artillery shortfall is now a national security crisis. Current efforts to make good for a lost generation, trying to catch up to the Russians in gunnery, are promising but long overdue. This crisis was years in the making and will be years in the unmaking.

The U.S. Army should therefore face the prospect of doing battle with Ivan with healthy trepidation for a good while yet. Their track record is not encouraging. Historically, our army has a habit of losing opening battles, often badly, due to unreadiness, as at Kasserine Pass in early 1943 and with Task Force Smith in the summer of 1950. In the past, there has always been time to learn lessons from defeat and catch up. The next time there may not be.

Underestimating the Russians, particularly in gunnery, has a long and undistinguished history. In the summer of 1914, the Austro-Hungarian Army went to war against the tsar’s forces with unwarranted confidence. Vienna’s artillery situation resembled ours today, with their units facing Russians armed with more, better, and longer-ranged guns. Disaster followed, as recounted in my recent book Fall of the Double Eagle, with Habsburg forces being literally blasted off the battlefields of Galicia by superior enemy artillery. Austria-Hungary lost 420,000 men in just three weeks, the entire strength of the prewar army, and never recovered. This is the fate the U.S. Army must avoid.