The U.S. State Department has accused Russia of building up additional air defense systems in eastern Ukraine. State Department spokeswoman Marie Harf said in a statement Wednesday that Moscow has also built up forces along the Ukrainian border, which is a violation of a ceasefire agreement signed in Minsk in February.

Russia Building Air Defense Systems In Eastern Ukraine: US

Russia moving its defense systems closer to the front line

Harf said, besides deploying additional air defense systems, Russia has moved “several of these nearer the front line.” After maintaining a steady presence along the Ukrainian border, Russia is sending more troops there, accused the State Department. American officials are not sure whether these military maneuvers are preparations for a new Moscow-backed offensive.

The fighting between Ukrainian government forces and Russian-backed separatists has claimed more than 6,000 lives since last year. Harf noted that the Russian forces and separatists have maintained communications and “command and control” equipment in eastern Ukraine that they could use to organize an attack. The United States said that Russia was actively training separatists in the area, reports Reuters.

An unmistakable sign of Russia’s presence

The Minsk agreement stipulates that all armed groups and weapons must be withdrawn from the Ukrainian territory. Russia is violating the truce by keeping multiple rocket launchers and artillery in eastern Ukraine. Harf accused that separatist forces were conducting “increasingly complex training,” including with drones, in the restive eastern part of Ukraine. It was “an unmistakable sign of Russia’s presence.”

A few days ago, United States sent 300 of its paratroopers in Ukraine to conduct a joint military training with the Ukrainian national guards. Russia reacted strongly to the U.S.-Ukraine military exercise, saying that such a move could “destabilize the region.” Moscow says Washington’s aggressive behavior in eastern Europe had forced it to act in Ukraine.

Ukraine and Western countries have repeatedly accused Russia of supplying weapons and providing training to separatists in eastern Ukraine. But Moscow has denied the charge.