STORY: Taipei's government has complained of a rising threat from China.
"The U.S. Department of Defense is now proactively planning cooperation between the U.S. National Guard and Taiwan's defence forces," Tsai said during a press event with visiting U.S. Senator Tammy Duckworth in Taipei.
Tsai noted that Duckworth was one of the main sponsors of the Taiwan Partnership Act, which had received bipartisan support in the U.S. Congress but has yet to become law.
Duckworth said she was visiting to reiterate that her country stands with Taiwan, and that there was "tremendous" support for the island from U.S. lawmakers.
The visit comes after U.S. President Joe Biden angered China by appearing to signal a change in a U.S. policy of "strategic ambiguity" on Taiwan by saying the United States would get involved militarily if China were to attack the island.