Vladimir Putin has become a global menace.

There is an irrefutable link between the Russian leader’s reckless policies on Ukraine and the downing of Malaysia Airlines Flight 17. This tragedy is the direct outgrowth of his decision to train and arm Ukrainian separatists with heavy weapons in an effort to destabilize Ukraine.

It doesn’t matter whether the triggerman thought he was targeting a Ukrainian military plane rather than a civilian airliner. More than 200 European civilians, along with dozens of Aussies, Asians and North Americans, lie dead because of Putin’s determination to force Ukraine to join a new Russian empire.

These deaths should serve as a wake-up call to feckless European leaders who have refused to follow President Barack Obama’s lead and impose tougher sanctions on Russia. The moment is now.

Western investigators have had difficulty gaining access to the scattered airplane wreckage because of pro-Russian separatists, even as the damning evidence of Russian complicity piles up.

The current crop of Ukrainian separatist leaders are mostly men with Russian citizenship or passports, including their military commander Igor Girkin (also known as Strelkov), a longtime agent of the KGB’s successor agency, who now works with Russian military intelligence. The recently elected Ukrainian president, Petro Poroshenko, has pursued a dialogue with separatists and offered to decentralize government power, but he has been rebuffed by the rebels. With Russian support, they have consistently violated cease-fires.

In recent weeks, Kiev retook significant territory in eastern Ukraine; Putin backed off his threat to invade as Western economic sanctions (even weak ones) began to bite.

At the same time, however, Russia was pouring heavy weapons — including tanks, artillery, rocket launchers, shoulder-fired missiles and other antiaircraft weapons — across the border into Ukraine.

This brings us to the subject of the Russian-made “Buk,” or SA-11 surface-to-air missile system, which Western intelligence analysts believe shot down Flight 17.

On June 29, Russian TV and Internet sites claimed that Ukrainian rebels had seized a Buk launcher from a Ukrainian army base, and rebel websites began bragging that they now had such a system.

On July 14, rebel sites said they had used the Buk to shoot down an An-26 Ukrainian military transport aircraft at 21,000 feet. They also claimed to have shot down a Ukrainian Su-25 jet on July 16.

In other words, the rebels suddenly acquired the capacity to shoot down planes at very high altitudes. But military experts say extensive training is required to master the operation of the Buk system; this would not have been possible if the missile system was recently seized from the Ukrainian army.

The Ukrainian government insists that Russian trainers and military were behind all the shootdowns, military and civilian. They say their An-26 and Su-25 planes were targeted from the Russian side of the border. They also say that Russia sent a Buk system across the border, complete with an operating team, early in the morning of July 17 — the day the Malaysian plane went down. The missile launchers, they add, were driven back to Russia hours after the crash.

However the rebels obtained the Buk, the evidence indicates they indeed fired it, although they appear not to have realized they were targeting civilians. Right after the plane crashed, a post went up on Girkin’s website bragging that rebels had just shot down a Ukrainian army plane, a claim that was picked up immediately by all Russian media. “We did warn you,” Girkin allegedly said. “Do not fly in our sky.”

After the news broke of the civilian disaster, Girkin’s website scrubbed all references to the shootdown. So did Russian media websites, which also removed week-old posts congratulating the rebels on acquiring Buk missiles. However, screenshots of the old posts are still widely available on social-media sites.

Obviously, the evidence must be fully vetted. We can expect that Putin, with the straight face he perfected as a KGB agent, will continue to deny Russian involvement and blame everything on “Ukrainian fascists.” But, as Obama said Friday, “We don’t have time for propaganda. We don’t have time for games.”

The Russian leader has destroyed a decades-long peace in Europe by invading a neighboring country. He has stirred up a “rebellion” that is led by Russian citizens, and fueled by Russian heavy weapons, training and hysterical media.

And now, by providing separatists with long-range missiles, which required Russian trainers, he bears responsibility for the death of hundreds of innocent people. In the words of Polish Foreign Minister Radoslaw Sikorski, “This is how delivering advanced weapons to bandits ends.”

Obama had announced new, tougher U.S. sanctions early last week, but Europeans had declined to follow. He should continue to press them. Their weakness has encouraged Putin’s dangerous behavior.

“It is time for the Europeans to show the European Union is not a jellyfish,” says John E. Herbst, the former U.S. ambassador to Ukraine who is now at the Atlantic Council. “Cowardice on the part of the Europeans is no longer acceptable.”

Surely doing justice to the memories of 200 innocent European men, women and children requires European leaders to stand up to Putin, now.

Trudy Rubin is a columnist for the Philadelphia Inquirer.