Threats of a pre-emptive nuclear strike. Refusing to answer a hotline phone. Announcing the ending of the armistice.

Even by North Korean standards, the threats this week by leader Kim Jong Un and ensuing actions have been incredibly provocative, making the situation on the Korean Peninsula more worrisome.

Here's a look at the Kim's escalating rhetoric and his country's actions since he came to power following his father's death in 2011:

March 2012

As South Korea hosts world leaders at an international nuclear security summit in Seoul, North Korea moves a long-range rocket toward a launch pad.

Pyongyang says it plans to carry out the test in mid-April as part of a commemoration of the 100th anniversary of the birth of Kim Il Sung, the nation's founder.

April 2012

Defying warnings by U.S. President Barack Obama that Kim has nothing to gain from provocations, Pyongyang launches the rocket. It breaks apart and falls into the sea.

August 2012

Kim visits the same military unit behind a 2010 attack on South Korea's Yeonpyeong Island, where he reminds the troops to be ready to fight a "sacred war" against Seoul.