Reuters

By Holly Ellyatt, Jun. 16, 2015, CNBC

Russia-West relations took a downturn this week when Moscow warned that any stationing of military equipment along its border with Europe could have "dangerous consequences" and President Vladimir Putin announced that Russia would add more than 40 ballistic missiles to its nuclear arsenal this year.

At a military and arms fair on Tuesday, Putin announced the addition of the intercontinental ballistic missiles which, he said, were able to overcome "even the most technically advanced anti-missile defense systems."

After the announcement, Jens Stoltenberg, the secretary-general of the North Atlantic Treaty Organization (NATO), said that Putin's statement was one reason why the international military alliance was upping its deterrence measures.

The Russian Foreign Ministry issued its warning on Monday against military presence on its western border after the New York Times and other media organizations reported that the U.S. had offered to store military equipment for up to 5,000 troops—including battle tanks and heavy weapons—in allied eastern European countries.