By CHRISTOPHER BODEEN, Associated Press

TAIPEI, Taiwan (AP) — Strongly pro-Taiwan U.S. Sen. Tammy Duckworth is visiting the self-governing island democracy to discuss regional security and relations with the U.S.

Duckworth, an Illinois Democrat, will hold a series of high-level meetings with senior Taiwan leaders to discuss U.S.-Taiwan relations during her visit Wednesday and Thursday, said the American Institute in Taiwan, which acts as the de-facto American embassy in Taiwan in liu of formal diplomatic relations.

Trade, investment and “other significant issues of mutual interest” also are on the schedule, the institute said.

“The visit underscores the United States’ commitment to its partnership with Taiwan and reaffirms our shared commitment to strengthening a Free and Open Indo-Pacific,” the institute said.

China routinely protests such visits, which it views as a violation of U.S. commitments.

Duckworth and her staff are the second U.S. congressional delegation to visit Taiwan in as many days, demonstrating concerns in Washington over the island’s security in the face of Chinese threats to invade, as well as its importance as a trade partner, particularly as the producer of 90% of the world’s most advanced computer chips.

Taiwan also faces 32% tariffs under the Trump administration, a figure the government in Taiwan is attempting to negotiate to a lower level without angering sectors such as agriculture that fear lower tariffs could open their markets to heightened competition from abroad.

Duckworth is visiting at the same time as Lourdes A. Leon Guerrero, the governor of Guam, the U.S. Pacific territory that would almost certainly be a key player in any Chinese military moves against Taiwan.

Taiwan and China split during a civil war in 1949 and Beijing still considers the island its own territory to be annexed by force if necessary. China refuses all contact with the government of President Lai Ching-te, whom China brands as a separatist, and seeks to maximize diplomatic pressure on Taiwan.

While China sends military aircraft, ships and spy balloons near Taiwan as part of a campaign of daily harassment, special attention has been given this week to the location of the Liaoning, China’s first aircraft carrier, whose hull was bought from Ukraine and then fitted out by China more than a decade ago. China has two aircraft carriers including the Liaoning, a third undergoing sea trials and a fourth under construction.

“What I can tell you is that the activities of the Chinese warship in the relevant waters are fully in line with international law and the basic norms of international relations,” Chinese Foreign Ministry spokesperson Mao Ning said.

Col. Hu Chung-hua of the Taiwanese Defense Ministry’s’ intelligence department told reporters Wednesday that the carrier was currently in waters southeast of Taiwan and has been under close surveillance by Taiwan’s monitoring stations since leaving its home port in China.

There are concerns the carrier might stage military drills close to Taiwan that could be a further step toward a blockade, an act the U.S. would be required to respond to under its own laws. While the U.S. provides much of Taiwan’s high-tech military hardware, the law is unclear whether it would send forces to aid Taiwan in the event of a conflict.

Hu said the ministry would not comment on the possibility of drills near Taiwan, but considers all options while monitoring the Chinese military.

The ministry “anticipates the enemy as broadly as possible and defends against the enemy strictly. We also carefully evaluate and act accordingly,” Hu said.

China is considered a master of “grey-zone encounters” that bring tensions just to the point of breaking out into open conflict.

Col. Su Tong-wei of the ministry’s operation of planning said the armed forces were constantly evaluating threat levels to consider whether to “activate a response center, or to increase our defense readiness to perform an immediate readiness drill.”

“We will also react accordingly to safeguard national security,” Su said.