TAIPEI -- Taiwanese President Tsai Ing-wen toured NASA's Johnson Space Center in Houston, Texas, on Sunday, becoming the island's first sitting leader to set foot in an American government facility in the U.S.

The visit, highlighting the close ties between Taiwan and the U.S., appears aimed at checking China's efforts to absorb the island. Although China has yet to react officially to Tsai's visit, it may have a vociferous response.

Tsai's itinerary included the Mission Control Center and other facilities, Taiwan's Central News Agency reported. Tsai stopped in Houston on her way home from a roughly weeklong tour of Central and South America.

"Astronaut Michael Fincke told me that the beautiful lights of Taiwan were visible from the space station passing over," Tsai wrote on Facebook.

Tsai also visited the Ronald Reagan Presidential Library near Los Angeles at the start of her trip on Aug. 13, making a speech praising Reagan's contributions to U.S.-Taiwan relations.

Tsai's tour of the Americas is part of the island's effort to be recognized as self-ruled and democratic, and distinct from China. "In going abroad, the whole world can see Taiwan. They can see our country as well as our support for democracy and freedom," Tsai said, before her flight to Los Angeles. "We only need to be firm, so that no one can obliterate Taiwan's existence.

The Taiwanese president's visit to the U.S. was treated as a stopover. Tsai was on an official visit to Paraguay and Belize, two of the remaining 18 countries that maintain diplomatic ties with Taipei. Her visit was aimed at ensuring that they do not switch recognition to Beijing.

Paraguay may be tempted to do so. China is forging closer ties with the South American country, as higher U.S. tariffs on soybeans exported to China encourage it to look for new suppliers, including Paraguay.

China hopes to gain control over Taiwan, and it has been pressuring other countries and companies not to recognize Taiwanese sovereignty. Beijing has ordered foreign companies to specify that Taiwan is part of China on their websites.

As a courtesy to China, the U.S. traditionally places strict limits on media appearances by the Taiwanese president on American soil. But Washington has recently played up its ties with Taipei, sending a message to Beijing amid rising tensions between the two countries over trade and geopolitics in Asia.

U.S. President Donald Trump in March signed the Taiwan Travel Act, which encourages high-level government exchanges between the U.S. and Taiwan.

Masayuki Yuda in Tokyo contributed to this report