In Taipei, Ms Pelosi praised Taiwan for having "one of the freest societies in the world".
China claims the self-ruled island as its own, and a foreign ministry spokesman said earlier this week that any visit by Ms Pelosi would be "a gross interference in China's internal affairs".
Beijing also warned that "the Chinese People's Liberation Army will never sit idly by" in the face of such a move.
And on Wednesday morning, Taiwan's defence ministry said the island will firmly defend its security, counter any move that violates territorial sovereignty and enhance its alertness level with the principle of not asking for war.
China's Xi Jinping in conversation with Russia's Vladimir Putin
Reuters
Cindy Yu in the GB News studio
GB News
Amid the heightened risk of conflict, Cindy Yu – host of The Spectator’s Chinese Whispers podcast – visited the GB News studio.
Appearing on Breakfast with Isabel and Mark, Ms Yu was asked about comparisons being made between Xi Jinping and Vladimir Putin as commentators fear a repeat of Russia's invasion of Ukraine with China and Taiwan.
GB News' Mark probed Ms Yu on whether "there is a parallel with Putin" and if Xi "wants to be seen as the strong man".
She explained that, unlike Hong Kong, Taiwan "hasn't been reunited in China's mindset" and that Xi thinks "his job is not done".
But there is a clear difference between Taiwan and Ukraine that makes Xi's position far more difficult than Putin's was prior to his invasion of Russia's European neighbour.
Ms Yu said: "One difference, though. Taiwan, it has been a flourishing democracy.
"Now, I’m not a Russia expert but Ukraine has had less time being a flourishing, independent state.
"So, the task on China’s hands is much tougher.
"The military task is also much harder because it’s an island. China has to be better at joint operations: land, sea and air.
"It’s a much tougher task than just marching over some ground."