WASHINGTON, Feb. 13 - In the months before North Korea announced that it possessed nuclear weapons, the Bush administration began developing new strategies to choke off its few remaining sources of income, based on techniques in use against Al Qaeda, intelligence officials and policy makers involved in the planning say.

The initial steps are contained in a classified "tool kit" of techniques to pressure North Korea that has been refined in recent weeks by the National Security Council. The new strategies would intensify and coordinate efforts to track and freeze financial transactions that officials say enable the government of Kim Jong Il to profit from counterfeiting, drug trafficking and the sale of missile and other weapons technology.

Some officials describe the steps as building blocks for what could turn into a broader quarantine if American allies in Asia - particularly China and South Korea - can be convinced that Mr. Kim's declaration on nuclear weapons last week means he must finally be forced to choose between disarmament and even deeper isolation. China and South Korea have been reluctant to impose penalties on the North.

To some degree the effort arises from Washington's lack of leverage over North Korea, and the absence of good military options, and it is far from clear that the administration's development of what one official calls "new instruments of pressure" will work. More than four decades of economic embargos of Cuba, tried by nine presidents, have failed, largely because European, Canadian and Latin American allies have not joined in. Nor have they succeeded against the Burmese, also a major source of drugs. The Secret Service has tried for years to halt North Korean counterfeiting, and Australia and Japan have tried to end its sales of amphetamines and heroin.

In interviews over the past three weeks, administration officials have denied that the renewed effort is part of an unstated initiative to topple Mr. Kim. But several officials say North Korea has stepped up its illicit trafficking and counterfeiting in part to make up for lost missile sales and a crackdown on cash transfers from North Koreans living in Japan, some of which are illegal.

"We think they are desperate to put more money into the nuclear program and we're trying to cut that off," said one senior official.

Some officials acknowledge that undermining Mr. Kim's hold on power could be a side effect of the program, if it was successful. "That wasn't the intent in drafting it," said one senior official who involved in the process. "Whether it could be one of the results is anyone's guess."

Several officials cautioned, however, that the new "tool kit" did not yet constitute a plan of action because the United States was only slowly trying to engage other nations in the strategy. They said some of the new techniques had already been carried out, but would not say which ones.

Details of the "tool kit" were described by officials in one intelligence agency and two other government agencies. One official of a foreign government who has been briefed on parts of it confirmed some of the elements. On Sunday evening, Scott McClellan, the White House press secretary, cast the effort as "complementary to our continued diplomatic efforts," but insisted that some of the techniques had been used for some time.

"We have been working with our allies and partners for some time now to stop North Korea's illegal activities, especially in counterfeiting and narcotics," he said. "We have a responsibility to protect our citizens, our allies and our economies. North Korea cannot continue its involvement in illegal activities. It must make a strategic decision and eliminate its nuclear weapons program."

Other officials said that while different agencies had been pursuing the North, the new effort was the first time the White House was coordinating and expanding the tactics to put more pressure on Mr. Kim.

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