Taiwan President Lai Ching-te kicked off his second day in the United States on Sunday, as China fumed over more US arms sales to the island and Lai's stopover in Hawaii that is part of his Pacific tour.
China, which claims Taiwan as part of its territory, opposes any international recognition of Taiwan and its claim to be a sovereign state.
Beijing especially bristles at official contact between the island and the United States, which is Taiwan's most important supporter and biggest arms supplier.
In his first public speech of the trip, Lai said Saturday that we have to "fight together to prevent war," warning there were "no winners" from conflict.
On the eve of his weeklong trip, the United States approved a proposed sale to Taiwan of spare parts for F-16s and radar systems, as well as communications equipment, in deals valued at $385 million in total.
China's foreign ministry called on the United States over the weekend to "immediately stop arming Taiwan and stop abetting and supporting 'Taiwan independence' separatist forces."
"China will take strong and resolute countermeasures to firmly defend national sovereignty, security and territorial integrity," it added.
In a separate statement, the foreign ministry said China "strongly condemns" the United States for Lai's stopover and that it had "lodged serious protests with the US".
Lai was greeted in Hawaii on Saturday with red carpets, garlands of flowers and "alohas", as he met with state Governor Josh Green, members of the US Congress, officials from the de facto US embassy in Taiwan and others.
While the United States has sold billions of dollars worth of arms to Taiwan, Washington has long maintained a "strategic ambiguity" when it comes to putting boots on the ground to defend the island from China.
Lai's remarks followed China's threats last week to "resolutely crush" any attempts for Tawain independence and ahead of US President-elect Donald Trump taking office in January.
Trump caused jitters during his campaign by suggesting Taiwan should pay the United States for its defense and accusing the island of stealing the US semiconductor industry.
Lai is scheduled to address the East-West Center in Honolulu on Sunday.
After Hawaii, he will visit Taiwan's allies the Marshall Islands, Tuvalu and Palau -- the only Pacific island nations among the 12 remaining allies that recognize Taiwan's claim to statehood -- and stop over for one night in the US territory of Guam.
Lai said shortly before take-off in Taipei that the trip "ushered in a new era of values-based democracy" and thanked the US government for "helping to make this trip a smooth one".
He said he wanted to "continue to expand cooperation and deepen partnerships with our allies based on the values of democracy, peace and prosperity."
"I once again emphasize that we are all Team Taiwan. We all work together, and we can successfully achieve our goals," Lai told reporters on board the plane.
An AFP journalist is travelling with the president for the duration of the trip.
