* Beijing can't control North Korea's Kim Jong-il
* North Korea's leader can't be trusted, China must lead
* US must not reward North Korea's bad behavior - Mullen (Recasts with comments, details)
By Phil Stewart
WASHINGTON, Nov 26 (Reuters) - The top U.S. military officer called on China to intensify pressure on North Korea and focus on leader Kim Jong-il's "vulnerabilities," saying that Beijing was wrong if it thought he was "controllable."
China has said it is determined to prevent an escalation of this week's violence on the Korean peninsula after North Korea shelled a South Korean island, the heaviest bombardment since the 1950-53 Korean War.
But Admiral Mike Mullen, chairman of the Joint Chiefs of Staff, said in comments released on Friday that North Korea's nuclear ambitions increase the threat of regional instability.
"It's hard to know why China doesn't push harder," Mullen, told CNN television's Fareed Zakaria GPS, in comments due to air on Sunday. "My sense is they try to control this guy. And I'm not sure he is controllable."
He added: "I think we all have to focus on getting his attention -- but in particular, China, in terms of focusing on his vulnerabilities and making sure that that part of the world doesn't come undone."
CNN released a transcript of the interview, recorded on Nov. 24.
Beijing has warned against military acts near its coast as U.S. and South Korean forces prepared for four days of naval drills in the Yellow Sea starting on Sunday.
The U.S. military said the exercises, planned long before Tuesday's attack, were designed to deter North Korea and were not aimed at China. It is sending an aircraft carrier group led by the nuclear-powered USS George Washington for the maneuvers.
"We've routinely operated in waters off the Korean peninsula for years," said Captain Darryn James, a Pentagon spokesman. "These latest provocations have been by the North and they need to take ownership of those, not us."
North Korea has entered an unpredictable period of leadership transition with the elevation of Kim Jong-il's youngest son, Kim Jong-un, in September to the rank of general -- in a clear sign he is the chosen successor.
Mullen has said he believes the artillery attack and the sinking in March of a South Korean warship, which the United States and South Korea blamed on the North, is likely linked to Kim Jong-il's "posturing" to allow the eventual succession.
But Mullen said the North Korean leader "is consistent and predictable only in his unpredictability," adding that Kim Jong-il should not be reward for his "bad behavior."
"He's not a guy we can trust," Mullen said. "That's why the leadership aspect of this from China is so important, because if any country has influence in Pyongyang, it's China," he said. (Editing by Christopher Wilson)
Our Standards: The Thomson Reuters Trust Principles.