Seoul, May 22 : South Korean President Yoon Suk Yeol, his US counterpart Joe Biden and Japanese Prime Minister Fumio Kishida could hold a trilateral summit in Washington as early as July, an official said here on Monday. "The possibility of holding a South Korea-US-Japan summit this summer in Washington is being talked about," the presidential official told Yonhap News Agency. The development comes a day after Biden had proposed such a summit when he met with Yoon and Kishida on the sidelines of the G7 summit in Hiroshima on Sunday. The three countries have been strengthening trilateral cooperation to deal with growing challenges stemming from North Korea's nuclear program, and China's military and economic assertiveness. During their brief meeting on Sunday, the three leaders agreed to upgrade trilateral cooperation to a new level, Yoon's office said. If the Washington meeting is realised, it will be the first time the leaders of the three countries will be meeting specifically for that purpose, not on the margins of a multilateral gathering. "Over the long term, this could develop into a form of shuttle diplomacy between the leaders of South Korea, the US and Japan," another presidential official said, referring to the leaders regularly visiting each other's countries, as done by the leaders of South Korea and Japan. /IANS