With the second North Korea-U.S. summit just a week away, the focus of that meeting has shifted from demands that Pyongyang immediately relinquish its nukes to whether the two parties have the wherewithal to lay the groundwork for such an ambitious goal in the long term, interviews with leading U.S. experts and statements by top officials from both countries have shown.

Ahead of U.S. President Donald Trump's meeting with North Korean leader Kim Jong Un in the Vietnamese capital of Hanoi on Feb. 27 and 28, more than eight months after their landmark summit in Singapore, diplomats from both sides were set to begin a second round of talks this week to reach an agreement.

Until recently, the two sides had made little progress in narrowing the glaring gaps in their interpretations of the vaguely worded document that emerged from the Singapore meeting. In that declaration, the U.S. committed to security guarantees for the Kim regime and the North pledged "to work toward the denuclearization of the Korean Peninsula."