A top White House adviser has personally delivered a pointed message to North Korean officials in New York, urging them to act on a nuclear disarmament pledge and telling them that US patience is limited, a US official said.

The United States and South Korea today agreed that they will not treat North Korea as a nuclear state, indicating a difficulty at revived disarmament talks with Pyongyang that has claimed it is a full atomic power.

North Korea’s No. 2 leader said today any progress at revived talks on the communist nation’s nuclear program will depend on the United States, according to a news report, an indication that any breakthrough at the negotiations could be difficult.