China will sanction Lockheed Martin for involvement in the latest U.S. arms sale to Chinese-claimed Taiwan, Beijing said on Tuesday, adding tension to its troubled relationship with the United States.

The U.S. weapons maker is the main contractor for a $620 million upgrade package for Taiwan’s Patriot surface-to-air missiles, which the U.S. government approved last week.

Chinese foreign ministry spokesman Zhao Lijian called on the United States to stop selling weapons to Taiwan to “avoid further harming Sino-U.S. ties and peace and stability in the Taiwan Strait”.

“To safeguard the country’s interests, China has decided to take necessary steps, and put sanctions on the main contractor for this sale, Lockheed Martin,” Zhao told reporters, without giving details.

Lockheed Martin said in a statement: “Foreign Military Sales are government-to-government transactions and we work closely with the U.S. government on any military sales to international customers. Discussions about sales to foreign governments are best addressed by the U.S. government.”

The United States, like most countries, has no official diplomatic ties with Taiwan, but Washington is bound by law to provide the island with the means to defend itself.

China has announced similar sanctions before on U.S. companies for Taiwan arms sales, though it is unclear what form they have taken.

The government in Taiwan has welcomed the missile upgrade. It is bolstering its defences for what it sees as increasingly threatening moves by Beijing, such as its regular air force and naval exercises near Taiwan.

Taiwan Defence Minister Yen Teh-fa, visiting troops during the annual Han Kuang military exercise on Tuesday, said they needed to be strong in the face of “all sorts of threats and provocations” from China.

“This tells our people and the Communists that we have the confidence and ability to protect our people and homeland,” his ministry cited him as saying.

While Taiwan’s military is well-trained and well-equipped with mostly U.S.-made hardware, China has huge numerical superiority and is adding advanced equipment of its own such as stealth fighters and new ballistic missiles.

Reuters