North Korea's attack on a South Korean island appears to be tied to the leadership succession, a top U.S. military official said Wednesday, as the elderly and frail Kim Jong Il prepares to hand control of his regime to his son. 

Adm. Mike Mullen, chairman of the Joint Chiefs of Staff, said in an interview on "The View" that Kim is generating these kinds of high-profile and dangerous confrontations to coincide with the ascension of his 27-year-old son to power. 

Mullen said the United States is working with its South Korean and Japanese allies and also looking to China to exert its influence. The State Department said Wednesday that the administration wants China to restrain the North from further provocative acts. Spokesman P.J. Crowley, calling China "pivotal," said U.S. diplomats sent the message to Chinese officials in Washington and Beijing that the country has to make clear to Pyongyang that its actions are not acceptable. 

The deadly strike on the tiny island came just six weeks after the North Korean leader unveiled his youngest son Kim Jong Un as his heir apparent. Analysts described the attack, which followed a claim that the country has a new uranium enrichment facility, as a cry for attention at a critical juncture. 

Recent reports show the damage on the South Korean side to be worse than previously thought. Rescuers found the burned bodies Wednesday of two civilians. That was after two South Korean marines were killed and nearly 20 people were injured. 

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As South Korean troops remained on high alert and buildings continued to burn, a U.S. aircraft carrier strike group set off for Korean waters. President Obama called South Korean President Lee Myung-bak Tuesday night, saying the U.S. would work with the international community to strongly condemn the attack. 

The White House said the two presidents agreed to hold combined military exercises and enhanced training in the days ahead to continue the close security cooperation between the two countries. 

Obama described North Korea's attack as a "provocative" show of force that "needs to be dealt with." 

"This is a -- just one more provocative incident in a series that we've seen over the last several months," Obama said in an interview with ABC, adding that he will be consulting with South Korea's president about their response. "We strongly condemn the attack, and we are rallying the international community to put pressure on North Korea." 

He wouldn't comment on the likelihood of military action, but called it "a serious and ongoing threat that needs to be dealt with." 

Rep. Pete Hoekstra, R-Mich., ranking Republican on the House intelligence committee, said the strike and its timing raises "serious questions" about Kim's succession. 

"Could the increase in high-profile attacks by North Korea in advance of Kim's expected succession by his son Kim Jong Un signal a period of increased hostility on the peninsula?" Hoekstra said in a statement. "Will there be more deadly, unprovoked attacks leading up to and following his ascension to power?" 

That possibility had many leaders calling Tuesday for tough action against North Korea. 

Hoekstra urged the United Nations Security Council, which is set to hold an emergency meeting, to "condemn this attack in the strongest terms." 

South Korea's president called for "enormous retaliation" in the wake of the clash. While pushing for "peace and stability" in the region, the White House also vowed to stand by its ally and labeled North Korea's attack an "outrageous act." 

The attack on the island of Yeonpyeong was the latest in a series of provocations from the Communist country. South Korean officials said the North launched the attack after warning the country to halt military drills in the area. 

A senior U.S. military official told Fox News the attack was nevertheless "unprovoked." 

"No one is interested in escalating this, but we are taking this very seriously," the official said. 

It's unclear whether there were any casualties on the North Korean side. There are about 28,000 U.S. military personnel in South Korea. 

The Associated Press contributed to this report.