China's recent offer of aid to North Korea could undermine UN sanctions against Pyongyang and help feed a cycle of failed negotiations aimed at ending the isolated country's nuclear programme. A former US nuclear negotiator for North Korea said this in Seoul today. Last week, Chinese Prime Minister Wen Jiabao visited the impoverished North, which relies heavily on outside assistance to feed its people, armed with a reportedly 20 million US dollar aid package. In return, North Korean leader Kim Jong II told Wen he would rejoin six-party nuclear disarmament negotiations if direct talks with the US were fruitful. Wen's trip came as North Korea began to take a series of conciliatory steps after months of raising tensions including staging nuclear and missile tests. Analysts say the about-face shows the regime is feeling the pain of UN sanctions adopted with Chinese support to punish Pyongyang for the May nuclear test.