In late July, the Trump administration announced that the U.S. Army’s V Corps headquarters would be reactivated and permanently stationed in Poland. The Kremlin, its Twitter bots and Russian President Vladimir Putin’s propaganda twits objected. Chinese Communist Party flacks likely hissed (if so, I missed it).

Reactions throughout still-free Europe were either quiet nods of agreement or reserved acceptance. These reactions reflect strategic reality. (1): Putin’s nuclear-armed Russia is an expansionist threat that requires military deterrence. (2): Russia has demonstrated its military and political threat overtly and covertly from the Scandinavian arctic south through the Baltic States to the Black Sea and Mediterranean Sea.

Russia’s 2014 invasion and annexation of Crimea and endless blood-spilling aggression in Ukraine have had political consequences in ostensibly neutral Finland and Sweden. In 2018, Finland and Sweden agreed to increase security coordination and conduct more joint military exercises with the U.S. In 2019, NATO held an exercise to repel an “aggressive power,” which had attacked Finland and Norway. NATO aircraft supported Finnish forces in Finland. As for the Black Sea flank, Russia invaded Georgia in 2008.

Poland is the lynchpin of NATO’s current eastern flank.

The Kremlin understands that a U.S. Army Corps headquarters is more than generals and flags. A corps HQ is structured, equipped and manned to coordinate every weapon and surveillance system in the Pentagon’s and allied arsenals, from space-based assets to submarine-launched weapons. As an Army unit, V Corps would focus on ground and air combat, but when required, it has the joint warfare connectivity to control air and naval systems. Applicable Pentagon buzz terms include “interoperability” and “synchronizing tactical formations.” Beyond the jargon, the V Corps presence tells Russia that invading Poland could quickly ignite a high-intensity war, with lethal consequences for Russia.

Rotational U.S. Army ground combat units already serve in Poland. Rotational means they deploy and then return to a base outside of Poland. Poland is building infrastructure for at least 5,500 U.S. military personnel. In all likelihood, the Pentagon will permanently station at least one “heavy” (armor) brigade in Poland.

Some of the soldiers moving east may come from Germany. Quick-shot critics jumped the Trump administration for the decision to reduce U.S. forces in Germany, painting the decision as Donald Trump spiting Germany’s Angela Merkel.

Give the critics a map and 12 years of news updates. Let’s agree that the 21st-century NATO vs. Russia cold war is a small-case version of the 20th-century Cold War. But Russia’s invasion and annexation of Crimea and invasion of eastern Ukraine aren’t small-case imperialism. Russian hybrid war — political meddling, information warfare, narrative warfare, economic threats, covert attacks and assassination — is a powerful and disruptive cocktail that savages Ukraine and threatens still-free Europe. The war in Ukraine’s east, the Donbass, continues, receiving scant major media coverage.

The front’s moved east, and strategically, Poland is where West Germany was circa 1960.

Poland is a worthy and responsible American ally that pays its fair share. The Polish government spends more than 2% of GDP on defense and recently agreed to pay the majority of stationing costs for permanently based U.S. troops. The defense ministry is committed to building forces equipped with an array of high-tech weapons designed to stop Russian tank and mechanized units. The Polish army wants to modernize its tank fleet, acquire late-model M1 Abrams tanks and add a fourth ground division by 2025. To defend its airspace, Poland has purchased F-16 fighters and Patriot missile defense batteries. The Polish Air Force will acquire 32 F-35 Joint Strike Fighters.

Soft diplomatic power has its place. But the Kremlin’s violent bullying has spurred frontline Poland to invest in its own hard military power, supported by a Cold War-like U.S. Army trip-wire force armed with 21st-century sensors and weaponry.

Austin Bay is a syndicated columnist and author.