The top nuclear negotiators of the United States and North Korea will meet in Singapore Thursday to discuss Pyongyang’s nuclear verification efforts.

U.S. envoy Christopher Hill and his North Korean counterpart Kim Kye-kwan are expected to fine-tune the details of a plan verifying the North’s nuclear programs the two officials drafted in Pyongyang in October.

Their discussions are likely to focus on how to include the issue of nuclear sample extraction from the North's key nuclear facility in the verification protocol.

Washington has repeatedly said it wants the sampling issue in writing, but the North’s foreign ministry said last month that it never agreed to include sampling in the protocol.

Hill met with the top nuclear envoys from South Korea and Japan in Tokyo on Wednesday. The officials agreed that sample extraction is imperative to thorough nuclear verification.

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