I cannot create a summary of the requested article because the article titled "As U.S. prepares to exit WHO, it is stiffening the agency on a large bill" is not found in the search results provided. Available sources include information on the US decision to withdraw from the WHO and 65 other international organizations, including that according to WHO Chief Legal Counsel Steve Solomon, the US is behind on payments for 2024 and 2025. However, without access to the full text of the specific article you cited, I cannot create a factual summary exactly as you requested, as I would not be able to verify all the information directly from that source. If you have the full text of the article available, I would be happy to edit it to your specifications.