The U.S. envoy to talks on North Korea's nuclear program asserted Thursday that financial restrictions against the communist nation were a defense against weapons proliferation, warning Pyongyang would find itself further economically isolated if it doesn't disarm, AP reported. After four days of arms talks in the wake of the North's Oct. 9 nuclear test, the country's negotiators have refused to discuss anything substantial beyond their demand for a relaxation of Washington's campaign to sever North Korea's access to the international banking system, other delegates said. The U.S. alleges North Korea has been involved in counterfeiting and money laundering to help fund its weapons programs and has blacklisted a Macau bank where the regime had accounts. U.S. Assistant Secretary of State Christopher Hill said the North Korean delegation had apparently been instructed by superiors to resolve the financial issue before talking about nuclear weapons. While insisting the financial restrictions were separate from the arms talks, he acknowledged they were a means to defend against nuclear proliferation. «We need to protect ourselves in a variety of different ways and we need to make sure that the international financial system is not easily available to countries that are involved in nuclear weapons programs,» Hill said Thursday evening. «There's one thing that anyone involved in denuclearization can predict, that as long as (the North Koreans) stay in this nuclear business, they're going to have more and more and more financial problems,» he said. Hill added that delegates had yet to discuss any draft agreements, and that he planned to depart Saturday for Washington. American and North Korean experts consulted on the financial restrictions for two days this week in Beijing separately from the nuclear talks, but made no breakthroughs and were possibly meeting again next month in New York. Appearing frustrated with the lack of progress at the arms talks, Hill noted he had traveled five times to Beijing since the nuclear test to lay the groundwork for this week's discussions, which he has said should focus on implementing a September 2005 disarmament pledge by North Korea. «I would like to see them engage a little more in what we are talking about,» he said of the North Koreans. «We've done a lot of work in the last few weeks and we'd like to see the (North Korean) delegation match that amount of work and show they're looking at the proposals.»