US senator visits Taiwan as China ups military threat

US Senator Tammy Duckworth meets with Taiwan's President Tsai Ing-wen at the Presidential Office in Taipei, Taiwan. Photo / AP

US Senator Tammy Duckworth has reiterated America's support for Taiwan on her second visit in a year to the self-governing island claimed by China.

Duckworth, meeting Taiwan President Tsai Ing-wen, emphasised the close economic, political and security relations between Taipei and Washington.

China sent 30 military aircraft towards the island on Monday in an ongoing campaign of regular flights. Taiwan's Defence Ministry said it responded by scrambling jets, putting air defence missile systems on alert and issuing radio warnings.

Duckworth said she wanted to "emphasise our support for Taiwan security". The former Army helicopter pilot and lieutenant colonel in the National Guard cited strong bipartisan backing for a bill she has put forward promoting cooperation between Taiwan's armed forces and the National Guard.

"It is more than just about military. It's also about the economy," the Illinois Democrat told Tsai.

Tsai thanked the US government and Congress "for the importance they place on peace and stability across the Taiwan Strait", as well as Duckworth herself for "keeping a close watch on Taiwan-related security issues".

China said it strongly deplores Duckworth's visit.

"Taiwan is a province of China, and there is no so-called president," Foreign Ministry spokesperson Zhao Lijian said. He urged the US to end all official contact with Taiwan.

"The US government has recently sent a series of erroneous signals on the Taiwan issue," he said. "What the US government should do is to put into practice President Biden's remarks that the US does not seek a new Cold War with China, does not aim to change China's system and does not support Taiwan independence."

US President Joe Biden said on a recent trip to Japan and South Korea that the US would intervene militarily if China were to invade Taiwan.

Russia's invasion of Ukraine has put China's threats against Taiwan under new focus, prompting increased backing for arms sales and political support from Democrats and Republicans.

China upped the ante last month, reaching out to the Solomon Islands and nine other island nations with a sweeping security proposal that, even if only partially realised, could give it a presence in the Pacific much nearer Hawaii, Australia, New Zealand and on the doorstep of the strategic American territory of Guam.

That is seen as a potential route to block access to Taiwan by the US and its allies if China makes good on its threat to invade the island.

In a speech Thursday, Secretary of State Antony Blinken said President Joe Biden's administration aims to lead the international bloc opposed to Russia's invasion of Ukraine into a broader coalition to counter what it sees as a more serious, long-term threat to global order from China. He did say that the US does not support Taiwan independence.

While relations with Taiwan are informal in deference to Beijing, the US remains its main supplier of defensive arms and source of political support in international organisations where China blocks Taiwan's participation.