The Trump administration has responded to China's threat to sanction U.S. companies selling weapons to Taiwan by approving the sale of anti-ship missiles to that country.

The administration's latest decision will step up pressure on China in the run-up to the presidential election Nov. 3, political experts said Tuesday. State Department representative Morgan Ortagus said China's sanctions were "entirely unacceptable."

Taiwan's Foreign Ministry said Tuesday the latest sale was the fourth this year and fully showed the U.S. government placed importance on Taiwan's defense needs.

It said arms sales to Taiwan were gradually becoming the norm and that it welcomed being able to acquire necessary defense equipment when needed.

China announced sanctions on Lockheed Martin Corp., Boeing Defense and Raytheon Technologies Corp. Monday. Hours later the U.S. approved the latest sale of the missile defense systems costing $2.37 billion to Taiwan. The weapons are made by Boeing Defense.

"The U.S. maintains an abiding interest in peace and stability in the Taiwan Strait and considers the security of Taiwan central to the security and stability of the broader Indo-Pacific region," the department said. It said the sale wouldn't alter the military balance in the region.

However, China's Ministry of Foreign Affairs representative Zhao Lijian had said earlier: "We will continue to take necessary measures to safeguard national sovereignty and security interests."

"In order to safeguard national interests, China decided to impose sanctions on the American companies that were involved in arms sales to Taiwan."

He said U.S. arms sales to Taiwan "seriously violate" the one-China principle and harmed China's security interests. Zhao also called on the U.S. to stop selling weapons to Taiwan and to sever military ties with the government of Taiwan President Tsai Ing-wen.

Zhao didn't explain the nature of the sanctions. He did, however, say the sanctions will apply to "relevant U.S. individuals and entities that played a negative role in the arms sales." He named Lockheed Martin, Boeing and Raytheon.

The Trump administration two weeks ago informally told the U.S. Congress of its intent to sell sophisticated weapons to Taiwan. It accelerated the pace of weapons sales to Taiwan this year as tensions between Taiwan and China rose.

In addition, the Trump administration has told Congress of its intent to sell more weapons to Taiwan.