In the shadow of the World Cup in Brazil and the new crisis in Iraq, the situation in Ukraine has become more serious. For the first time pro-Russian separatists in the east of the country have been supplied with heavy weapons. The latest reports say that separatists even shot down a Ukrainian military plane with at least 49 people on board in the early hours of Saturday (14.06.2014).

Three T-64 tanks crossed the border from Russia on Thursday (12.06.2014), Ukrainian media reported - and the government in Kiev later confirmed. The tanks were advancing on Donetsk as they were attacked by Ukrainian forces.

An adviser to the Ukrainian interior minister said on Friday (13.06.2014) the tanks had previously belonged to the Ukrainian army in Crimea. They were first shipped from the Russian-annexed peninsula to the Russian mainland and from there they were sent across the border into eastern Ukraine.

Arms shipments via the open border

These are serious allegations against Russia. Moscow sent convoys of weapons to Ukrainian separatists, Interior Minister Arsen Avakov said on Thursday in Kyiv.

For days, Ukrainian bloggers have reported that small convoys of army trucks with hundreds of fighters were rolling into Ukraine from Russia, loaded with tons of firearms, but also with armored personnel carriers and heavy guns.

This is possible because there is a huge hole in the border. "Unfortunately, the Ukrainian government has lost control of about 184 kilometers of the 2,200-kilometer border with Russia," a senior Ukrainian border official admitted in a newspaper interview. That section of the border, as well as the local border crossings, are under the control of separatists.

Moscow has been silent about the allegations from Kyiv. Early in June, Russian President Vladimir Putin rejected allegations of Russian interference in eastern Ukraine in an interview for French television. "There are no Russian troops in the southeast of Ukraine," he said.

Different tactics from Crimea and Georgia

Some observers in Ukraine believe the tanks mark a dramatic turn in the bloody conflict. "The Kremlin is showing its true face," the popular blogger and Kiev military expert Dmytro Tymtschuk wrote on Facebook. He said it was a blatant Russian invasion.

"Ukraine and Russia are practically at war," Mykola Sunhurovski of the Kyiv-based Rasumkov Centre NGO, said in an interview with Deutsche Welle. "The leaders in charge of the separatists in Ukraine as well as the mercenaries come from Russia," he said.

This time, Moscow is pursuing a different tactic than in February and March 2014 when it annexed the Crimean peninsula, or 2008 in its war against Georgia. Instead of long convoys of tanks and trucks, individual groups seep through the border and then spread across multiple locations. That makes it difficult to speak of an open invasion, Sunhurovski said.

No "peacekeepers" from Russia

Moscow military analyst Alexander Golz also does not currently see a Russian invasion in eastern Ukraine. "The scale of events speaks against this," he told DW. "It looks more like a classic covert operation."

It would only be possible to speak of an "invasion" if not only individual military advisers or tanks, but entire units were used - as in Crimea. "Russia has abandoned the invasion plans and wants maximum destabilization of Ukraine " Golz said. The reason is the inadequate resources of the Russian army and the western threats of sanctions.

For weeks the separatists in eastern Ukraine have been calling on Moscow to send battle tanks, heavy weapons and even "peacekeepers." But the calls are getting louder to invade, even in Russia itself. "We do not believe that things have gone that far," Russian Foreign Minister Sergei Lavrov said on Thursday. But Russia is now supplying what it describes as "humanitarian aid" to the people of eastern Ukraine. Because Kyiv opposed this, Russia had been forced to work with "self defense" forces, Lavrov said.

Third stage of sanctions under discussion

With Russian tanks on Ukrainian soil, the conditions would be met for the third and final stage of Western sanctions against Russia. In the spring, the European Union and the US had threatened to impose economic sanctions against Russian companies, should Russia invade eastern Ukraine.

NATO Secretary General Anders Fogh Rasmussen expressed concern at the reports about weapons and even tanks from Russia: "If these reports are confirmed, this would mark a serious escalation of the crisis in eastern Ukraine." The response of the German government to the reports was similar: "If confirmed, that would indeed be a serious and very worrying development," government spokesman Steffen Seibert said in Berlin on Friday.

The Ukrainian Foreign Ministry raised the issue of further sanctions this week. "If Russia does not contribute to a de-escalation of the situation in eastern Ukraine, we will have to ask the international community to impose new sanctions," Foreign Minister Andrii Deshchytsia said. He called on Moscow to stop its tanks, armored trucks and mercenaries from crossing into eastern Ukraine.