A U.S. Air Force B-52 bomber flies over Osan Air Base in Pyeongtaek, South Korea, last month. (Ahnn Young-Joon/Associated Press)

JUST A few years ago, in the Obama administration’s fiscal 2013 defense budget summary, the word “Russia” was mentioned briefly in the context of the new strategic arms treaty. By contrast, in the fiscal 2017 summary, President Obama proposes spending increases for “countering Russian aggression,” including the quadrupling, to more than $3 billion, of funds for deploying a persistent Army brigade in central and eastern Europe, with training and prepositioning of combat gear. The shift is late, and the funding only a down payment. But the recognition that Russia has evolved from hoped-for partner to serious threat is welcome.

The intent of the increased spending is to reassure allies made nervous in the face of Russia’s new aggressiveness and “send a strong message of deterrence.” Russia and its militia proxies are occupying parts of three former Soviet republics — Moldova, Georgia and Ukraine — and its military has taken the initiative in Syria, propping up the regime of Bashar al-Assad. Across Europe the Russians are waging a nasty information war, using overt and covert methods to undermine NATO and the European Union. Many Western officials believe that Russian leader Vladi­mir Putin is deliberately exacerbating the refu­gee crisis that threatens European unity, a tactic they refer to as the “weaponization of migration.”

Meanwhile, while the U.S. military concentrated on counterinsurgency warfare during the past decade, Russia was making impressive advances in electronic warfare and other military technologies. Like China, Russia has a smaller defense budget than that of the United States but has been sinking resources into weapons systems that are “asymmetric,” meaning that a relatively small investment can undermine a formidable conventional U.S. capability. Russia, for example, has reportedly developed a new unmanned nuclear-capable underwater drone, while China is improving its anti-satellite capability. Both have leapfrogged technology hurdles, in some cases by stealing blueprints from the United States.

How to respond? Obama’s budget doubles Air Force offensive cyber-operations from $12.8 billion to $25 billion, according to Defense One. The budget contains money for research and development on railguns and lasers, swarming autonomous vehicles, guided munitions, electronic warfare and more technology wonders that remain in classified budgets. While Western allies must continue the fight against the Islamic State and other forces of instability, they also must recognize that, through no choice of their own, a new age of deterrence has dawned. The United States must strive to hold on to technological superiority and make clear to Russia that further aggression would impose an unacceptable cost.