Negotiators from six nations agreed have agreed on steps to verify North Korea’s nuclear disarmament, opening the final phase in tortuous efforts to rid the North of nuclear weapons.

The agreement, reached Saturday after three days of talks, said North Korea would finish disabling its biggest nuclear facility by the end of October while the United States, China and the other three parties would complete promised deliveries of fuel oil and other economic aid.

Beyond that, the envoys agreed to a robust verification team of experts who will visit North Korean nuclear facilities, review its documents and interview its technical experts.