To understand the mental schema of the US strategic ambiguity we have to keep in mind the following five points. They belong to the report of the Congressional Research Service.
1. The US didn’t explicitly state the sovereign status of Taiwan in the 3 US-PRC Joint Communique of 1972, 1974 and 1982.
2. The US “acknowledged” the “one China” position of both sides of the Taiwan Strait.
3. US policy hasn’t recognized the PRC’s sovereignty over Taiwan.
4. US policy hasn’t recognized Taiwan as a sovereign country.
5. US policy has considered Taiwan’s status as unsettled.
The positions remained unchanged until 2013.
In 2016, President Trump and the ROC President Tsai Ing-Wen spoke about the close economic, political and security ties between the US and Taiwan.
In 2017, President Trump agreed to honor the “one China” policy at the request of the PRC Paramount leader Xi Jinping.
In 2022, President Biden said that the US would intervene militarily if China were to unilaterally invade Taiwan.
This was the Ukraine’s effect.