The People’s Republic of China is tightening its bond with one of Asia’s most strategic small countries while President Biden fortifies ties with the defensive Indo-Pacific network that he cultivated in nearly four years in the White House.

The election of a Marxist president of Sri Lanka, an island nation of 23 million people off India’s southeastern coast, at once boosts the prospects for China exploiting a controversial port that it built for the troubled country overlooking the seas linking Asia to the Middle East. 

A once obscure radical politician, Anura Kumara Dissanayake, head of the far-leftist National People’s Power Party, garnered 42 percent of the votes, far ahead of the leader of the main opposition party, who got 33 percent, and the incumbent president, 17 percent, in a field of 34 candidates. That plumbs the outrage over economic difficulties that led to famine on an island noted for its agricultural output, especially tea.

The Chinese party boss, Xi Jing Peng, fired off a congratulatory message pledging to work with Mr. Dissanayake on China’s signature Belt-and-Road program linking the People’s Republic, by sea and land, through Asian countries to the Middle East and Europe. Sri Lanka occupies a pivotal position in the middle of the “string of pearls” that China has fostered across South and Southeast Asia, building ports and other facilities capable of serving military as well as commercial purposes.

Mr. Xi’s message did not hint at the criticism accompanying China’s growing presence in Sri Lanka and the region.

“Surging investment from China, including a multibillion dollar oil project late last year, is leaving a giant question mark over Sri Lanka,” said Nikkei Asia, an offshoot of Japan’s financial paper, Nihon Keizai Shimbun. “China is the largest bilateral creditor to Sri Lanka,” Nikkei said. “Chinese loans had financed a string of large infrastructure projects, including highways, an airport and a port.”

China’s foreign ministry spokesman, Lin Jian, heaped scorn on a meeting that Mr. Biden hosted at his old high school near Wilmington with the other leaders of the Quad, Prime Ministers Kishida, Modi, and Albanese. The Quad, said Mr. Lin, is “a tool the U.S. uses to contain China and perpetuate U.S. hegemony.” 

The Indian press is reporting an embarrassing moment when Mr. Biden seemed to have forgotten Mr. Modi’s name.