China has voiced its "firm opposition and strong condemnation" after the United States administration announced its largest arms sale package planned for Taiwan, totaling $11.1 billion.

The arms sales plan was unveiled on Wednesday, covering eight items, including HIMARS rocket systems, howitzers, Javelin anti-tank missiles, Altius loitering munition drones and parts for other equipment, Reuters reported.

Foreign Ministry spokesman Guo Jiakun said on Thursday that the US move assisting separatism with arms will only backfire, and its attempt to "contain China through Taiwan" will never succeed.

China urges the US to stick to the one-China principle and the three China-US joint communiques, "act on the serious commitments made by US leaders, and immediately stop the dangerous practice of arming Taiwan", Guo told a daily news conference in Beijing. "China will take resolute and strong measures to defend its national sovereignty, security and territorial integrity," he said.

This move "seriously disrupts peace and stability across the Taiwan Strait", and sends a greatly erroneous signal to "Taiwan independence" separatist forces, Guo noted.

The spokesman said the Taiwan question is "the core of China's core interests" and "the first red line that must not be crossed in China-US relations". "No one should underestimate the firm will and strong capability of the Chinese government and the Chinese people in safeguarding national sovereignty and territorial integrity," he said.

"Taiwan independence" separatist forces attempt to "advance their 'independence' agenda" and resist reunification through military buildup, squander taxpayers' money to purchase weapons and even risk turning Taiwan into a "powder keg", Guo said.

This will not reverse the inevitable failure of "Taiwan independence", and will only push the Taiwan Strait into the danger of military conflict at a faster pace, he said.

In November, the US Department of Defense approved an arms sales package, consisting of aircraft parts worth about $330 million for Taiwan, marking the first such sale by the current administration.

Chen Binhua, a spokesman for the State Council Taiwan Affairs Office, urged Washington on Thursday to stop condoning or supporting "Taiwan independence" separatist forces and to "handle the Taiwan question with utmost prudence".

"The reunification of the motherland is unstoppable. If any 'Taiwan independence' separatist forces dare to cross the red line, we will deliver a resolute, head-on blow," Chen said.

Japan's move slammed

In another development, the Japanese Defense Ministry signed a land lease agreement on Monday for deploying a mobile radar system on the easternmost island of Okinawa to monitor Chinese aircraft carriers and airplanes in waters between Okinawa's main island and Miyako Island.

The deployment is due to begin in 2026, with an estimated 30 personnel to be stationed there.

Guo, the Foreign Ministry spokesman, said that Beijing has noted the reports and stressed that "countries enjoy freedom of navigation and overflight in the relevant waters and airspace in accordance with international law". He said that Japan kept strengthening targeted military deployments near China's Taiwan region and even claimed it will deploy midrange missiles. Tokyo "has now gone even further by deploying a radar unit and troops to secretly monitor its neighbor".

"People should ask whether Japan is making trouble and provocations to cover up and justify its own military buildup and maritime ambitions, and whether it is following the designs of right-wing forces to once again move along the evil path of militarism to a dead end," he said.

"We urge Japan to learn from history," he added.

zhangyunbi@chinadaily.com.cn