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. Victor Cha, President George W. Bush's top adviser on North Korea, and a State Department official told the North Koreans on Tuesday that frustration is rising 10 days after the North missed a deadline to shut down its main nuclear reactor, according to a senior US official with knowledge of the meeting. "Everyone's waiting on North Korea to act," said the official, who spoke on condition of anonymity because of the sensitivity of the issue. "We don't have all the time in the world. We have patience, but patience is limited."