TOKYO, Dec 11 (Reuters) - Japanese companies said strained diplomatic relations with China are their primary concern as they head into 2026, followed closely by U.S. trade policies, a Reuters survey showed on Thursday. Ties between ​the Asian neighbours have deteriorated since Japanese Prime Minister Sanae Takaichi told parliament last month that a ‌hypothetical Chinese attack on democratically governed Taiwan could trigger a Japanese military response. Asked what makes companies most concerned when for ...