WASHINGTON — President Joe Biden is set to establish diplomatic relations Monday with two South Pacific nations, the Cook Islands and Niue, as his administration aims to show to Pacific Island leaders that it is committed to increasing American presence in the region.

       The announcement comes as Biden prepares to welcome leaders to Washington for a two-day U.S.-Pacific Island Forum Summit expected to focus heavily on the impact of climate change.

       Biden has put a premium on improving ties in the Pacific amid rising U.S. concern about China’s growing military and economic influence. Plans for the diplomatic move were confirmed by two senior administration officials who briefed reporters on the condition of anonymity before the formal announcement.