Washington, Jan. 18 (CNA) Members of the Taiwan Caucus in the United States Senate on Friday sent a congratulatory letter to President Tsai Ing-wen on her reelection to a second term in the Jan. 11 presidential election.

"As longstanding friends of Taiwan, we write to congratulate you on your reelection as President of Taiwan," the senators said.

They also wished Tsai continued success in promoting Taiwan's democracy "at the heart of a free and open Indo-Pacific region."

"We also congratulate the people of Taiwan, whose determination and resilience made another free election in Taiwan possible," they wrote.

The senators said Taiwan is a critical economic and security partner for the U.S., and that they look forward to working with Tsai and her government to advance mutual interests.

Meanwhile, the senators also expressed condolences over the Black Hawk helicopter crash in Taiwan earlier this month, which killed eight officers, including Chief of the General Staff Shen Yi-ming.

The letter was signed by the 22 senators of the Taiwan Caucus, including James Inhofe, Robert Menendez and Charles Grassley.

According to Taiwan's Ministry of Foreign Affairs (MOFA), some 79 members of the U.S. Congress have sent congratulatory messages to President Tsai since her landslide election victory on Jan. 11.