Serbia began cooperation and dialogue with NATO in 2006, when the country joined the Partnership for Peace programme and the Euro-Atlantic Partnership Council. The country's military neutrality was formally proclaimed by a resolution adopted by Serbia's parliament in December 2007, which makes joining any military alliance contingent on a popular referendum, a stance acknowledged by NATO. On the other hand, Serbia's relations with Russia are habitually described by mass media as a "centuries-old religious, ethnic and political alliance" and Russia is said to have sought to solidify its relationship with Serbia since the imposition of sanctions against Russia in 2014.