Sen. Marsha Blackburn, R-Tenn., landed in Taiwan for an unannounced visit on Thursday, according to a source familiar with the trip.

Blackburn is only the latest in a series of U.S. lawmakers to fly to Taiwan, a trend that has outraged the Chinese government. House Speaker Nancy Pelosi visited the self-governed island in early August, and she was the highest-level U.S. official to do so since Speaker Newt Gingrich in 1997.

The Pentagon declined to comment on Blackburn's trip, stating that it does not comment on security details.

"We of course take all appropriate measures to ensure the safety of Members of Congress wherever and whenever they choose to travel," a Pentagon spokesperson told Fox News Digital.

China, which has long claimed Taiwan as its own territory, argues the trips infringe on its sovereignty.

No other lawmakers are accompanying Blackburn on the visit. The senator was already on her way home from a foreign trip visiting Fiji, the Solomon Islands and Papua New Guinea this week, according to a Thursday morning statement from her office.

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Marsha Blackburn senate hearings Kentaji Brown Jackson

Sen. Marsha Blackburn, R-Tenn., listens to senators' opening statements during the confirmation hearing for Judge Ketanji Brown Jackson, President Biden's nominee for Associate Justice to the Supreme Court, on March 21, 2022. (Bill Clark/CQ-Roll Call, Inc via Getty Images)

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Taiwan's Foreign Minister Joseph Wu, left, speaks with U.S. House Speaker Nancy Pelosi as she prepares to leave in Taipei, Taiwan, on Aug. 3, 2022. (Taiwan Ministry of Foreign Affairs via AP)

"The Indo-Pacific Region is the next frontier for the New Axis of Evil," Blackburn said in a statement that did not mention her visit to Taiwan. "Meeting with leaders from Fiji, the Solomon Islands and Papua New Guinea was an important step in showcasing America’s commitment to the region and expanding our strategic relationships."

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"Continuing these long-established partnerships is important to the success of both East Asian nations and the United States. I am grateful for their leadership. We must stand against the Chinese Communist Party," she added.

Blackburn's visit is the latest since five members of Congress landed in Taiwan in mid-August. The group, led by Sen. Ed Markey, D-Mass, included Reps. John Garamendi, D-Calif.; Alan Lowenthal, D-Calif.; Don Beyer, D-Va.; and Amata Radewagen, R-AS.

China has argued that visits by U.S. lawmakers infringe on America's One China Policy, which states that the U.S. acknowledges the Beijing government as the sole government of China.

China reacted to the previous August visits by launching live-fire military exercises surrounding Taiwan in an apparent rehearsal for an invasion.

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Taiwan first split from mainland China following a civil war between democratic and communist forces in 1949.

While the U.S. has agreed not to hold formal diplomatic relations with Taiwan, it has supplied the government with means of defense and other support.

Liz Friden contributed to this report.