A U.S. effort to show unity between two of its closest allies backfired after Japanese and South Korean officials walked out and left the No. 2 American diplomat to face reporters on her own.

Deputy Secretary of State Wendy Sherman was forced to give a solo news conference Wednesday in Washington following three-way talks with her Japanese and South Korean counterparts. Sherman described the discussions on issues including Chinese pressure on Taiwan and North Korea’s nuclear weapons program as "very constructive,” and attempted to play down the dust-up.

"There are some bilateral differences between Japan and the Republic of Korea that are continuing to be resolved, and one of those differences, which is unrelated to today’s meeting, has led to the change in format for today’s press availability,” she told reporters.