MOSCOW – If Vladimir Putin's ends remain mysterious, so do the means.

Putin is allocating unprecedented amounts of secret funds to accelerate Russia's largest military buildup since the Cold War.

The part of the federal budget that is so-called black — authorized but not itemized — has doubled since 2010 to 21 percent and now totals $60 billion, the Gaidar Institute, an independent think tank in Moscow, estimated.

Stung by sanctions over Ukraine and oil's plunge, Putin is turning to defense spending to revive a shrinking economy. The outlays on new tanks, missiles and uniforms highlight the growing militarization that is swelling the deficit and crowding out services such as health care. Thousands of army conscripts will be moved into commercial enterprises for the first time to aid in the rearmament effort.

"The government has two urgent tasks: strengthening security at all levels of society and promoting innovation," said Ruslan Pukhov of the Center for Analysis of Strategies and Technologies and an adviser to Moscow's Defense Ministry. "The solution to both problems is to intensify the development of the military-industrial complex."

Since bringing the country back from the brink of bankruptcy a decade and a half ago, Putin has increased defense spending more than 20-fold in rubles. In dollars, it exceeded $84 billion last year, more than any other nation except the U.S. and China, according to the Stockholm International Peace Research Institute.

Defense and the related category of national security and law enforcement now eat up 34 percent of the budget, more than double the ratio in 2010. The U.S., by comparison, spent 18 percent, or $615 billion, of its budget last year on defense and international security.

After studying Putin's actions in Ukraine, including his seizure of Crimea, the National Defense Academy of Latvia, a former Soviet satellite that is now part of NATO and the European Union, concluded that Russia's ultimate aim is to introduce "a state of permanent war as the natural condition in national life."

"We can and must do for the defense industry what we did for Sochi," Putin said on May 12, referring to the $50 billion Russia spent on the 2014 Winter Olympics. "All questions relating to adequate resource allocation have been resolved."

That same day, Putin signed documents creating what he called the "industrial battalions" program, which will give thousands of draftees the option of working in defense enterprises instead of joining the regular military.