Updated

BANGKOK -- The Obama administration is consulting with allies on a new "comprehensive package" of incentives aimed at persuading North Korea to abandon its nuclear programs, senior U.S. officials confirmed Tuesday.

The officials, who are traveling with Secretary of State Hillary Clinton in Thailand, told reporters that the package is only in its early stages and will not be offered to North Korea unless and until the allies sign off on it. Pyongyang would also have to first take specific, concrete and "irreversible" steps to begin destroying its arsenal of nuclear weapons.

The aides said that the administration needs to see concrete action. Mere assurances from North Korea that it will take action in the future would not be enough to trigger the presentation of the incentives package, they said.

The United States, though, has not yet conveyed to the North Koreans what the "irreversible" steps might entail, as Washington continues discussions with its allies in the so-called Six Party Talks.

The aides, who work on North Korea policy for three separate agencies in the U.S. government, portrayed the development of the new package as the second track of a two-track approach.

The first track consists of continued aggressive enforcement, also in conjunction with other nations across the globe, of U.N. Security Council Resolution 1874 -- which gives U.N. member states increased authority to interdict the flow of weapons and possible nuclear material in and out of North Korea.

The aides made clear they expect the two-track approach to remain in place for the foreseeable future.

"This is not going to be resolved in a couple of weeks," one official said. "This could be a sustained, substantial effort that could go on quite a long time."

The package of incentives would include some elements that are "familiar" from the Six-Party talks, the officials said, as well as new ones and some that differ in their "dimensions."

The United States, China, Japan, South Korea and Russia are the other participants in the long-running -- and long-stalled -- Six-Party Talks aimed at persuading North Korea to abandon its nuclear programs.

The emphasis on consultation with these other countries derives, the officials said, from the perception among some of them that the Bush administration did not adequately confer with them prior to the removal of North Korea from Washington's list of state sponsors of terrorism last year.

"The Japanese do have anxieties about engagement of North Korea," one official said.

The officials also echoed the "growing concerns" about reports of a military relationship between North Korea and Burma that Clinton voiced earlier Tuesday in a news conference with Thailand's deputy prime minister.

"It would be destabilizing for the region" if such reports were true, Clinton said, adding, "It would pose a direct threat to Burma's neighbors. And it is something, as a treaty ally of Thailand, that we are taking very seriously."

Briefing reporters after Clinton's news conference, the senior officials said their concerns range from suspicions that North Korea is supplying small arms to Burma to reports of possible nuclear collaboration between the two countries. Pressed on the nuclear question, the officials refused to discuss classified intelligence data but noted North Korea's history of proliferation with Syria. One aide said the possibility of nuclear collaboration between Pyongyang and Burma is "one of those areas that we would like to know more about."

To that end, U.S. intelligence agencies are studying recently published photographs purporting to show an elaborate set of underground tunnels that North Korea has built along Burma's border with Thailand. The officials said they see "some similarities" between the tunnels in the photographs and a network of underground tunnels in North Korea, the existence of which the United States learned about in the 1990s.

Both North Korea and Burma, a repressive military dictatorship whose leaders have renamed the country Myanmar, have been the target of broad sanctions by successive U.S. administrations over the last decade.

Clinton said Tuesday she would like to see Washington develop a "more productive" relationship with Burma, starting with steps by the government to release political prisoners and dissidents jailed there.

"We are very much engaged with partners such as Thailand and others in assessing and determining not only what is going inside of Burma but also what we can do effectively to change the direction and behavior of the Burmese leadership," Clinton said.