The switch has geopolitical significance that will be felt as far away as Washington because the Solomon Islands are located directly between Australia and the U.S. and were the site of fierce battles during World War II.
Alex Akwai, a spokesman for Solomon Islands Prime Minister Manasseh Sogavare, said the government's caucus took a poll on Monday, with 27 lawmakers voting in favor of switching allegiance to China and six abstaining. He said the Cabinet then voted unanimously in favor of the change.
Akwai said the Taiwanese Embassy in the capital, Honiara, had lowered its flag on Tuesday. Embassy staff declined to comment.
Taiwanese President Tsai Ing-wen said it will close the embassy and recall all technical and medical staff stationed there.
"We sincerely regret and strongly condemn their government's decision to establish diplomatic relations with China," Tsai said.
China, meanwhile, said it welcomed the Solomon Islands into its Pacific family.
"China highly commends the decision of the Solomon Islands' government to recognize the one-China principle and sever the so-called 'diplomatic ties' with the Taiwan authorities," Foreign Ministry spokeswoman Hua Chunying said in a statement.
China considers Taiwan to be part of its territory and wants to bring the island back into its fold. Taiwan split from mainland China during a civil war in 1949 and set up a rival government to the victorious Communists in Beijing.
Most countries recognize Beijing today, and China has been ratcheting up diplomatic and economic pressure to woo the remaining ones since Tsai took office in 2016.
With a population of 660,000, the Solomon Islands were easily Taiwan's largest remaining ally in the Pacific. Its economy relies on agriculture, fishing and forestry, and the country has a wealth of undeveloped mineral resources.
Now only 16 countries worldwide continue to recognize Taiwan, including five small Pacific nations. Of those, the Marshall Islands and Palau have close ties with the U.S. and are unlikely to switch allegiance anytime soon. But experts say Kiribati, Nauru and Tuvalu could soon switch.
U.S. Republican Sen. Marco Rubio said the U.S. shouldn't stay silent.
"The Solomon Islands has officially become the latest nation to bow to Chinese gov't pressure and sever ties with Taiwan," Rubio tweeted. "The U.S. and Int'l community must push back against Beijing's bullying and efforts to isolate #Taiwan."
James Batley, a researcher at the Australian National University and a former Australian high commissioner in the Solomon Islands, said the move didn't come as a surprise.
"The sense in Solomon Islands is that there are significant resources on offer here from China, and they want to move with the times and on the side of history," he said.
But he said the Solomons needs to be careful not to get into serious debt to China, particularly as, even before the switch, it was looking to take out big loans to fund infrastructure projects including a hydroelectric dam. He said Taiwan had promised the Solomons a new stadium for when it hosts the 2023 Pacific Games, and that the Solomons may now look instead to China for help.
Professor Anne-Marie Brady, an expert on China at the University of Canterbury, said the blow to Taiwan wasn't as big now as it might have been in the past. She said that's because Taiwan has managed to forge unofficial relations with dozens of countries and the European Union as part of a more pragmatic approach to its diplomacy.
She said the Solomon Islands may also benefit from being able to better balance its relations with a number of larger countries, including China, the U.S., Australia and New Zealand.
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