Russia has made the first move in an attempt to de-escalate the situation with Ukraine. With Ukraine accusing Russia of instigating the uprisings that allowed Crimea to secede and causing months of unrest in the country's eastern provinces, Russia has now begun to mobilize its troops away from border it shares with Ukraine. 

Defense Secretary Chuck Hagel said late on Thursday that Russian troops had begun to decamp and leave the border between Russia and Ukraine, according to the Washington Post.

Russia stationed around 40,000 troops near the border with Ukraine when violence and unrest began escalating during the Crimea crisis. Since then Russia has ignored calls by Ukraine, NATO and the United States to leave the country's border as the large military presence posed a threat to Ukrainian sovereignty.

With the Ukrainian presidential elections over and resurging violence in the east, Russia decided to withdraw the majority of its troops. The Washington Post reported, however, that about seven battalions -- some thousand troops -- remain along the border. Hagel told reporters aboard his plane that the withdrawal was "promising," but "they are not where they need to be and won't be until all of their troops... are gone."

According to NATO officials, about two-thirds of the Russian forces have withdrawn, but a sizeable enough force remains, capable of mounting an attack if needed, the Washington Post reported.

"Several thousand troops still remain in the vicinity, but most of these units appear to be preparing to withdraw," a NATO military officer said to the newspaper via email.

Following the shooting down of a Ukrainian helicopter carrying a general on Wednesday, President-elect Petro Poroshenko has vowed to retaliate, according to the Independent.

"These criminal acts of the enemies of the Ukrainian people will not go unpunished," he said, according to Unian news agency.