MEXICO CITY — President Tsai Ing-wen of Taiwan has been hopscotching across Central America this week, attending the inauguration of Nicaragua’s president, Daniel Ortega, touring Guatemala’s colonial city of Antigua and visiting the shrine of Honduras’s patron saint.

From a global perspective, it is the sort of tour that looks like a diplomatic asterisk. But there is nothing trivial about it for Ms. Tsai, who is in Central America to shore up relationships amid increasing pressure from China.

Taiwan, which China considers a breakaway province, has diplomatic relations with only 20 countries, along with the Vatican; the largest cluster of those is in Latin America and the Caribbean. These relationships, complete with embassies, trade agreements and foreign aid, strengthen Taiwan’s effective sovereignty.

That is particularly important now for Taiwan, which fears becoming a casualty as President-elect Donald J. Trump threatens to roil the China-America relationship. Mr. Trump accepted a congratulatory phone call from Ms. Tsai after his election, a break from protocol that prompted angry responses from China.