China and Taiwan are vying for influence over the Solomon Islands, in a diplomatic contest that could foreshadow conflict in the same place U.S. Marines fought a major battle during World War II.

The government of the Pacific Islands nation is in the early phase of a 100-day period to review diplomatic relations with Taiwan, the last holdout of the government overthrown when Chinese Communists came to power in 1949. The Beijing regime claims sovereignty over the self-governing island and has been lobbying world leaders not to recognize the independence of the government in Taipei. But a decision by the Solomon Islands in favor of China wouldn’t only be a victory for Chinese President Xi Jinping’s efforts to isolate Taiwan — it could also help China establish a useful outpost in advance of any clash with U.S. partners or allies in the Indo-Pacific.

“I think it shows what their true intent is,” said Florida Rep. Ted Yoho, the top Republican on the House Foreign Affairs subcommittee for Asia and the Pacific. “I think they’re building up for a conflict.”

Yoho’s fears are warranted, according to Mike Green, a top regional expert at the Center for Strategic and International Studies. The Solomon Islands’ location gives them strategic significance in the region, making their friendship valuable to China for the same reasons Allied forces fought the six-month Battle of Guadalcanal to take the islands from imperial Japan in 1942 and 1943.

“If a hostile power — at that time Japan — controlled those islands, it would cut off the U.S. ability to reinforce Australia,” said Green, a former senior director for Asia at the National Security Council under President George W. Bush.

The Solomon Islands, an archipelago of 600,000 people off the northeast shoulder of Australia, has long been among the least developed countries in the world. That relative weakness leaves them vulnerable to pressure from mainland China, the economic powerhouse that is by far the largest purchaser of the island’s exports.

“We are under a lot of pressure now to rethink this relationship,” Prime Minister Manasseh Sogavare told Australian media last week. “We have this relationship [with Taiwan] premised on some important fundamental principles with the United Nations, and it would be sad to see us moving away.”

Only 16 countries worldwide — 17, if you count the Holy See — recognize Taiwan as an independent nation. (The United States cut formal ties with the island government in favor of China during the Cold War, but lawmakers and presidents of both parties have sold weapons to Taiwan and maintained friendly relations over Chinese objections.) Foreign Affairs Minister Jeremiah Manele announced the 100-day review last week, which raises the prospect of a policy shift to come in September.

“They’re trying to isolate Taiwan, which we will not stand for,” Yoho said. “Taiwan is a very successful democracy 90 miles off their coast that allows freedom of expression, freedom of religion and all those things that China deplores. And so, anything they can do to isolate Taiwan they feel makes their hand stronger.”

China has launched a major diplomatic offensive against Taiwan in recent years, convincing three countries in 2018 alone to sever ties with Taipei and establish relations with his government instead. That effort has been greased by pledges of Chinese investment funding, which could tantalize Solomon Islands leaders.

Sogavare’s comments could induce Taiwan to redouble its own investment in the islands, a partnership that already includes “around $30 million in funds that are paid directly to members of Parliament for the sole purpose of developing their rural constituencies,” according to the Australian Broadcasting Corporation.

Western analysts worry that China will convince one of the Pacific Island countries to host a military base that could intensify their aggression closer to home.

“If they force the Royal Australian Navy to worry about its northeastern flank, or force the U.S. Navy to worry about the Pacific islands or Hawaii, that is that much less naval and air power we have to deal with the immediate crisis, whether it’s Taiwan or Japan or the Philippines,” he said.