Russia has successfully tested its capability to launch a massive retaliatory nuclear strike via land, sea, and air. The tests included the launch of missiles from a land-based silo, a nuclear submarine, and long-range bomber aircraft. The exercise comes as Russia is engaged in a tense standoff with the West over Ukraine. Russia, which has the world's largest nuclear arsenal, is also in the process of de-ratifying a nuclear test ban treaty to align itself with the United States. The tests were described as a rehearsal for a potential nuclear strike in response to an aggressor's attack.