North Korean leader Kim Jong Un, in his recent meetings with Russian, Chinese and U.S. counterparts, called for security guarantees instead of the lifting of sanctions in return for denuclearization, diplomatic sources said Friday.

Kim’s renewed focus on security guarantees could be an effort by Pyongyang to break the impasse in denuclearization talks with Washington, as the administration of U.S. President Donald Trump still regards sanctions as necessary until North Korea is completely denuclearized.

Ensuring the continuation of the current political system led by the Kim family is a long-sought goal by North Korea. In a joint statement issued after the first-ever U.S.-North Korea summit in June 2018, Trump promised to provide security guarantees to Pyongyang, while Kim committed to the “complete” denuclearization of the Korean Peninsula.

Senior officials of the Workers’ Party of Korea, North Korea’s ruling party, are likely to have already been briefed on Kim’s latest posture.

Concern remains, however, that in seeking security guarantees North Korea might in the future ask for a change in the configuration of U.S. military assets in the Asia-Pacific region, including troops stationed in South Korea, which could make nuclear talks more complicated.

If nuclear talks proceed between the United States and North Korea, Pyongyang is also likely to bring back its demand for sanctions relief on a premise that economic activities should be ensured to maintain the political system under Kim.

Until earlier this year, North Korea had called for U.N. sanctions, aimed at thwarting its nuclear and ballistic missile ambition, to be lifted, while claiming that it has started to take concrete measures toward denuclearization.

The U.S. government has been carefully analyzing what is behind the shift in North Korea’s negotiating strategy.

During his meeting with Trump at the inter-Korean truce village of Panmunjom on June 30, Kim did not make specific remarks about how to realize security guarantees promised to North Korea, according to the diplomatic sources.

The focus is on whether North Korea will make a detailed request at envisioned working-level talks between the two countries, which Washington has been eager to resume by the end of this month.

At the Feb. 27-28 summit in Hanoi, Vietnam, Kim and Trump fell short of a deal over the gap between Washington’s insistence on denuclearization and Pyongyang’s demand for economic sanctions relief.

Trump said at the time that Kim pledged to “totally” dismantle his country’s main nuclear complex at Yongbyon but that the lifting of the sanctions would require Pyongyang to scrap other nuclear facilities and programs, including undeclared ones.

In an apparent attempt to coax Washington into making concessions, Pyongyang warned in April that it would consider suspending denuclearization negotiations.

“In my opinion at this moment, it comes to my mind that there is no need for me to obsess over the summit talks with the United States out of thirst for the lifting of sanctions,” Kim said in his speech at the nation’s top legislature on April 12.

Kim is believed to have conveyed the intention to Russian President Vladimir Putin and Chinese President Xi Jinping. Kim met with Putin in late April in Russia’s eastern port city of Vladivostok and with Xi late last month in Pyongyang.

During working-level talks ahead of the failed summit in February, the United States and North Korea, which have no diplomatic relations, had broadly agreed to take steps to improve bilateral ties and establish permanent peace on the Korean Peninsula, such as opening a U.S. liaison office in Pyongyang.

The two countries were also preparing to declare an end to the Korean War, a 1950-1953 conflict that was halted with an armistice.

The U.S.-led United Nations forces had fought alongside South Korea against a North Korean invasion supported by China and the Soviet Union.

The United States has promised security guarantees before. The administration of President Bill Clinton, in a 1994 agreement with North Korea, stated, “The U.S. will provide formal assurances to the DPRK, against the threat or use of nuclear weapons by the U.S.” DPRK is an acronym for the Democratic People’s Republic of Korea, North Korea’s formal name.

The administration led by Clinton’s successor, George W. Bush, issued a joint statement with other negotiating parties, including North Korea, in September 2005 in which it affirmed that “it has no nuclear weapons on the Korean Peninsula and has no intention to attack or invade the DPRK with nuclear or conventional weapons.”

Both agreements fell apart as North Korea continued to develop nuclear weapons. No concrete measures were taken in the meantime to guarantee security for North Korea.

Among the arrangements likely considered forms of security guarantee for North Korea are converting the 1953 armistice into a peace accord and establishing diplomatic ties between the United States and North Korea.