KYIV — Tanks and other menacing self-propelled artillery. A Russian Buk surface-to-air missile system like the one that shot down Malaysia Airlines Flight 17 over eastern Ukraine in 2014. Thousands more troops.

Those are merely some of the Russian forces and matériel seen in videos posted to social media heading toward the Ukrainian border in the past week alone. Western and Ukrainian intelligence agencies estimate roughly 100,000 troops, along with fighter aircraft and ballistic missiles, are already in place. That number could increase to 175,000 soldiers, the agencies say.

These deployments, partnered with verbal threats and war games happening within striking distance of Ukraine, don’t bode well for peace in Eastern Europe. They are ominous signs that Russia may be preparing to launch another large-scale, multifront invasion to wrest back control of the former Soviet republic that has moved increasingly further from Moscow’s orbit — and toward the Western democratic world — since gaining independence 30 years ago.

An invasion, experts warn, could explode into the biggest and bloodiest war in Europe since World War II. But Russian President Vladimir Putin’s dangerous brinkmanship alone also threatens to drag the US and its allies in Western Europe, as well as NATO, deeper into the nearly eight-year-long war in Ukraine that has already killed more than 14,000 people. The Russian leader said he wants NATO to scratch its 2008 promise to Ukraine of future membership.

Recent satellite images provided to BuzzFeed News by Maxar Technologies and analyzed by military experts show what appear to be some of these new forces at strategic locations in Soloti, southwestern Russia, about 30 miles from the Ukrainian border, and in Opuk, southern Crimea, the Black Sea peninsula that Moscow forcibly seized from Kyiv in 2014.

By THM