GOP presidential candidate Mitt Romney on Monday called on the United States to take the opportunity of dictator Kim Jong-Il's death to push for regime change in North Korea, a distinctly different message than the calls for stability and caution coming from President Barack Obama's administration

"Kim Jong-il was a ruthless tyrant who lived a life of luxury while the North Korean people starved. He recklessly pursued nuclear weapons, sold nuclear and missile technology to other rogue regimes, and committed acts of military aggression against our ally South Korea. He will not be missed," Romney said in a Monday morning statement. "His death represents an opportunity for America to work with our friends to turn North Korea off the treacherous course it is on and ensure security in the region. America must show leadership at this time. The North Korean people are suffering through a long and brutal national nightmare. I hope the death of Kim Jong-il hastens its end."

The Obama administration has taken a different tone, urging caution and patience as power transfers to Kim's third son, Kim Jong Un. Obama was informed of the reports of the North Korean leader's death at 10:30 p.m. last night, and spoke at midnight with South Korean President Lee Myung-bak.

"The President reaffirmed the United States' strong commitment to the stability of the Korean Peninsula and the security of our close ally, the Republic of Korea" White House Press Secretary Jay Carney said in statement. "The two leaders agreed to stay in close touch as the situation develops and agreed they would direct their national security teams to continue close coordination."

The administration's stance is to not provoke the new leader, out of concern that he may take aggressive actions to demonstrate his strength both externally and within the top echelons of North Korea's political system.

"There's concern that Kim Jong-Un may now try to prove himself," a senior government official told ABC News. "He's young, inexperienced, brash and untested. And while he had the support of his father, it's unclear if he has the respect of his generals."

North Korea fired a short-range missile off of its east coast immediately following Kim's death, in a move some analysts believe was meant as a message to the South Korean security establishment and the 28,500 U.S. troops that are stationed on the Korean Peninsula.

White House Communications Director Dan Pfieffer said Monday morning that the White House has been in close contact with its allies, Japan and South Korea. He said he was not aware of any direct, high-level talks between White House officials and top leadership in Beijing. The State Department has yet to comment.