South China Sea
Chinese dredging vessels are purportedly seen in the waters around Mischief Reef in the disputed Spratly Islands in the South China Sea in this still image from video taken by a P-8A Poseidon surveillance aircraft provided by the United States Navy on May 21, 2015. Reuters/U.S. Navy

Update as of 4:23 a.m. EDT: After the United States vowed that it would continue to patrol international waters near disputed regions in the South China Sea, China said Friday that it was “strongly dissatisfied” with the U.S. government’s stance on the issue.

China also urged the U.S. to refrain from taking any risky and provocative actions, Reuters reported. “Such action is likely to cause an accident, it is very irresponsible and dangerous and detrimental to regional peace and stability,” Reuters quoted Hong Lei, a spokesman for China’s foreign ministry, as saying.

“China will continue to closely monitor the relevant area and take the necessary and appropriate measures to prevent harm to the safety of China’s islands and reefs as well as any sea and air accidents,” Hong reportedly said.

Original story:

The United States on Thursday vowed to continue air and sea patrols in international waters close to a disputed chain of islands in the South China Sea. The decision comes in the face of repeated warnings from the Chinese navy to abort the scouting mission.

On Wednesday, Chinese naval officials issued eight warnings to a P8-A Poseidon surveillance aircraft to vacate the area near a series of artificial islands being built by China near the disputed Spratly Islands, which have been claimed by several countries, including China, the Philippines, Malaysia, Taiwan, Vietnam and Brunei. However, a senior U.S. official said Thursday that the reconnaissance flight was “entirely appropriate,” and that the U.S. would “continue to fully exercise” the right to operate in the region's international waters and airspace, Reuters reported.

“Nobody in their right mind is going to try to stop the U.S. navy from operating - that would not be a good bet,” Reuters quoted Daniel Russel, the Assistant Secretary of State for East Asian and Pacific Affairs, as saying. “But it’s not enough that a U.S. military plane can overfly international waters, even if there is challenge or hailing query... We believe that every country and all civilian actors should have unfettered access to international waters and international airspace.”

The P8-A Poseidon, which was reportedly flying as low as 15,000 feet, was part of a mission to assess China’s progress in constructing military installations on the islands, and was reportedly investigating China’s rapid expansion in the region when the Chinese navy made contact with the crew.

“This is the Chinese navy … This is the Chinese navy … Please go away … to avoid misunderstanding,” a Chinese naval official was heard in a communication with the plane, according to CNN. An American pilot responded by saying that the plane was operating in international airspace.

Meanwhile, a spokesman for China’s Foreign Ministry said that other countries should respect China’s sovereignty in the South China Sea. “China has the right to engage in monitoring in the relevant airspace and waters to protect the country's sovereignty and prevent accidents at sea,” Reuters quoted the spokesman as saying.

U.S. officials announced last week that the country’s military was considering sending aircraft and Navy ships to enforce freedom of navigation around the rapidly expanding Chinese-made islands in the disputed waters of the South China Sea. According to the U.S., the man-made islands cannot be recognized as sovereign Chinese territory.

China has reportedly expanded the artificial islands in the Spratly Islands to 2,000 acres of land, which is significantly up from 500 acres last year. Recent satellite images also revealed that the country was building an airstrip on the northeastern side of Fiery Cross Reef, which is part of the Spratly Islands chain. On Thursday, the U.S. also released video containing footage shot from the P8-A Poseidon surveillance aircraft, which included details of military installations on Fiery Cross Reef.

In recent weeks, tensions between the U.S. and China have escalated, and the issue overshadowed last week's visit by U.S. Secretary of State John Kerry. And officials from both countries have issued statements designed to portray their hard-line stance on the issue.