No matter how painful sanctions may be, analysts say, Mr. Kim would be unwilling to give up his nuclear weapons unless an accord left him feeling completely safe without them. The security of his family-run regime is a nonnegotiable priority.

North Korea has emphasized that it wants security guarantees and will not trade its nuclear arsenal for economic benefits alone. It has also rejected assertions that it has been pressured into talks because of the pain of sanctions, adding that it does not expect help from the United States in pursuing economic development.

Indeed, the North Korean economy has been growing as much as 1 to 5 percent annually under Mr. Kim’s rule, because of a limited embrace of market forces by his government and, until late last year, loopholes in the multiple rounds of sanctions adopted by the United Nations Security Council.

Still, his apparent willingness to continue diplomatic efforts does suggest that Mr. Kim, 34, may be under pressure to satisfy rising expectations in North Korea for economic gains and shake off the painful grip of sanctions.

While largely depicted as a nuclear provocateur in the outside world, Mr. Kim is determined to be the face of a modern and more open North Korea at home. He has erected new buildings and repainted old ones in Pyongyang, the capital, attended a concert by a South Korean girl band and let a state orchestra play American pop music.

Mr. Kim has also sent party officials to China to learn its economic policies, and has even admitted to other failures during his supposedly faultless leadership, like a botched satellite launch in 2012. When he met with South Korea’s president, Moon Jae-in, last month and invited him to Pyongyang, he asked Mr. Moon to fly there because North Korea’s roads and trains were in such “embarrassing” condition.