South Korea has dismissed a "significant portion" of leaked US intelligence documents that reportedly suggest concern among top South Korean national security officials about arms manufactured by their country being sold to Ukraine. The documents are part of a wider leak, described by the Pentagon as "a very serious national security risk", that includes material on US spying on allies including South Korea and Israel. Photos of the documents have circulated across social media platforms and messaging services for weeks. US officials reportedly believe that many of the documents are genuine. The Pentagon has said that it is working to determine the truth, and that at least one document appears to have been manipulated. The leak will prompt concern for US allies, with South Korea having previously supplied non-lethal and humanitarian aid to Ukraine. Seoul has a longstanding policy against providing weapons to countries in active conflict, which makes it difficult to supply arms directly to Ukraine. The contents of the leaked documents could potentially affect the relationship between South Korea and both the US and Russia.