TAIPEI, Taiwan — Taiwan’s president, Tsai Ing-wen, will travel to the South Pacific on Thursday to shore up ties with three island nations that still recognize Taiwan as a country, in an effort to offset China’s expanding influence in the region.

Only 17 countries recognize Taiwan’s government, and among those, Ms. Tsai will be visiting Palau, Nauru and the Marshall Islands.

China has been pouring aid and investment into the Pacific islands, raising the question of whether Beijing could strip Taiwan of more of its few remaining diplomatic allies and shrink the self-ruled island’s international presence.

The Trump administration has sought to push back against China’s reach in the South Pacific and Latin America. Australia is also concerned, and last year set aside more money in its budget for Pacific aid.