More recently, Russia has given priority to improving its military hardware. Thus, it now has quality missile-defense systems, first-rate aircraft and substantial artillery. Putin has insisted upon massive investment in new high-tech equipment as a hallmark of his third term. The federal budget sent to the State Duma last September called for defense spending to increase from 3.4 percent of GDP in 2014 to 4.2 percent in 2015, with the bulk going to procurement.

The aim of this triumvirate of the nuclear backstop, more agile forces and more modern equipment is to enable Russia to assert military superiority on its western and southern borders, to establish a plausible defensive line in the east and to develop a capability to manage crises, particularly in the volatile Caucasus region.

HERE IS what these reforms have produced.

On the strategic nuclear level, Russia maintains effective parity with the United States. The two sides have roughly equivalent numbers of ICBM launchers, ballistic-missile submarines and nuclear-capable bombers. While Russian bombers are inferior to American aircraft, this does not affect overall strategic-weapons parity or Russia’s capacity to absorb a first blow and retain retaliatory effectiveness.

Missile-defense systems are a sore point. To Moscow’s consternation, Washington withdrew from the Anti-Ballistic Missile Treaty in 2002. The United States also sought to deploy missile-defense systems in Eastern Europe. While Moscow complains that these defenses hamper its retaliatory capability, in private they recognize that their offense can readily overcome this defense. Thus, it’s hard to see how these deployments contribute to Western security; it’s easy to see why they irritate Moscow.

The tactical-nuclear-weapons balance in Europe is overwhelmingly in Russia’s favor. The United States maintains some two hundred gravity bombs on six bases in five NATO countries and is currently modernizing these to give them a limited standoff capability. Russia, on the other hand, has a tactical force of several thousand warheads, of which some two thousand are believed to be active and assigned to naval, ground and air nonstrategic delivery vehicles.

Recently, Washington alleged Russian violations of the Intermediate-Range Nuclear Forces Treaty of 1987. Under its terms, both countries forswore all land-based cruise and ballistic missiles with a range between five hundred and 5,500 kilometers. The West is unsure about the seriousness of recent Russian moves in this arena, but it is concerned by Russia’s increasing reliance on nuclear posturing. Talk of first use is of special concern to NATO, particularly in light of the fifteen-year-old Russian doctrine regarding the use of a so-called deescalatory strike. This means nuclear strikes with the aim of restoring the status quo ante when Russia might otherwise lose. NATO is now struggling over whether to regard this as a bluff or a serious policy—and how to respond.

Insofar as Russia retains large armies for conventional war, these armies operate primarily in the Far East. Of the four regional Joint Strategic Commands into which the armed services are organized, only the Eastern Military District contains four army commands. In the event of a conventional invasion from China, two armies would serve as the first line of defense in the east with two more stationed farther west as a second defensive echelon. Air and naval standoff assets, including from the Pacific Fleet, would likely be used to delay hostile advances, while further reinforcements are drawn from the Central Military District.

Interestingly, for all of Russia’s wariness of China, it continues to sell Beijing high-quality weapons. It would not sell China such good equipment—and at very good prices—were it not desperate for money. Most notably, Moscow licenses the production in China of its SU-27 fourth-generation fighter and has done so since the 1990s.

The People’s Liberation Army currently numbers 1.6 million. At the first possible moment in an invasion, China would likely sever the Trans-Siberian and Baikal-Amur rail lines, thereby leaving Siberia isolated. The only strategic question for Russia in this scenario would be when to push the nuclear button.

Russia does not fear an invasion from its former Central Asian republics. The role of the Central Military District, based in Yekaterinburg, is to orchestrate Russian engagement in local conflicts within Central Asia, to manage Russia’s bases in Tajikistan and Kyrgyzstan, and to supply reinforcements from its two armies either to the east or the west in the event of war. There’s little to indicate that these forces are deployed to the central region for the purpose of reconquering lost Central Asian territories. Rather, their purpose is to forestall instability that might spill over into Russia and to remind everyone that Russia’s forces in the region are mightier than China’s.

Based in St. Petersburg, the Western Military District houses two army commands along with the Baltic Fleet, the Northern Fleet, numerous paratrooper brigades, Spetsnaz, air and air-defense units. Their role is to maintain clear military superiority along Russia’s western and northwestern borders, and to play a large part in air defense.

Russia’s air defenses are excellent. Their long-range surface-to-air missiles are among the best anywhere, particularly the S-300 and S-400 varieties. As mobile, truck-based units, they can secure air superiority over bordering regions, despite U.S. advantages in fighter aircraft. NATO reckons that Russian S-400s would have little difficulty taking down even American stealth aircraft within their 250-mile range. This likelihood greatly complicates any NATO strategy for establishing air superiority over the Baltic region. The United States is actively developing countermeasures to confuse or disable parts of Russian air defenses, but, all factors considered, any NATO effort to establish air superiority near Russian borders would be quite costly.

Russian fighter aircraft lack some of the power, precision and stealth of America’s best fighters, but are comparable to the F-15 and are a match for the F-22, according to American analysts and generals. Moscow is developing a fifth-generation stealth fighter, but currently relies upon the SU-27 Flanker and its more modern cousin, the SU-35.

Without the trial of battle, defense systems can be notoriously difficult to compare. Nonetheless, experts must and do make comparisons. In addition to being lighter and stealthier than their Russian counterparts, American F-22 and F-35 fighters may be equipped with the AIM-120 AMRAAM (Advanced Medium-Range Air-to-Air Missile) family of missiles that allow pilots to “fire and forget.” These missiles are thought to be superior to the Russian equivalent active-radar-homing missile, the R-77. Their potency, combined with the F-22’s superior radar, suggests that American planes would have considerable advantages in a fight over neutral territory. Unfortunately for NATO, fights are most likely to take place near Russia’s borders.

Other factors, ones that are even harder to measure, also influence airpower capabilities. American pilots receive more training hours each year and have more experience in coordinating combat operations with other branches of the military. Furthermore, Russia’s drive to develop fifth-generation fighters and bombers has, to some degree, been undertaken at the expense of developing better logistical capabilities such as refueling and troop transport. There is also the possibility that Russia’s new best-of-the-best equipment will prove less impressive in battle than on paper. India, a potential purchaser of the fifth-generation fighter, has complained repeatedly of unexplained technical malfunctions, charges reminiscent of those China has leveled after purchasing aircraft from the Russians.

The territorial remit of the Southern Military District, based in Rostov-on-Don, includes the unstable North Caucasus region, Russian bases in Abkhazia and South Ossetia, the base in Gyumri, Armenia, and now, most likely, Crimea. It is also responsible for operations in Ukraine. Even before that conflict erupted, the Southern district had the highest priority of all districts for new and modernized weapons and well-trained personnel. In addition to its two army commands, it oversees elite airborne troops, Spetsnaz and reconnaissance brigades, the Black Sea Fleet, the Caspian Flotilla and air units.

Southern forces can be quickly mobilized to respond to regional instability and, as was revealed in Ukraine, effectively deployed against Russia’s far weaker neighbors. They can maintain credible superiority along the country’s southwestern borders. Their takeover of Crimea was immediate, and relied heavily on elite formations.

Specialized Russian units performed so well in Crimea that Putin remarked after the annexation, “It was all coordinated so clearly, tightly . . . that I sometimes wondered: Was it really us?” Highly mobile and versatile, these units can be deployed in any of Russia’s strategic theaters.

Of the roughly 771,000-strong Russian military, fewer than a hundred thousand fight in elite formations. Of these, the number on par with NATO’s best is in the tens of thousands. Over the summer of 2014, Russia demonstrated the ability to draw as many as forty thousand troops to the Ukrainian border, including elite units. While this number was sufficient to menace Ukraine, it hardly represented a conventional threat to NATO forces in Eastern and Central Europe.

For the foreseeable future, the principal strategic danger for the United States and the West is on Russia’s western borders. China can take care of itself to the east, and Central Asia doesn’t worry about a Russian invasion, Putin’s occasional glowering at Kazakhstan notwithstanding. Russian armed forces don’t have the numbers, the allies or the logistical stamina needed to mount a credible threat to the former Warsaw Pact nations. It’s Ukraine, Moldova, Belarus and the Baltic states where the West needs an effective strategy for deterrence and containment.