Increasingly provocative behavior by China in the disputed South China Sea means it is "only a matter of time" before a major incident or accident occurs in the region, a U.S. Defense Department official warned Tuesday.

"In recent months, we've witnessed a sharp increase in unsafe and unprofessional behavior by PLA ships and aircraft, implicating not only U.S. forces but allied forces operating in the region," Ely Ratner, assistant secretary of defense for Indo-Pacific security affairs, told a think tank event in Washington, using the acronym for the People's Liberation Army, the Chinese military.

"In my view, this aggressive and irresponsible behavior represents one of the most significant threats to peace and stability in the region today, including in the South China Sea," he said.

"And if the PLA continues this pattern of behavior, it is only a matter of time before there is a major incident or accident in the region," he added.

China countered his claim on Wednesday, with Foreign Ministry spokesman Zhao Lijian telling reporters in Beijing that the country shares an aspiration with its Southeast Asian neighbors to ensure "peace and stability" in the waters.

He suggested the United States and its regional allies are the threats to peace and stability, saying "a certain major country" outside the region has been "frequently sending aircraft carriers and strategic bombers and rallying non-regional allies to flex their muscles" in the South China Sea.

"The South China Sea is not a place to be turned into a wrestling ground by big powers outside of the region," Zhao stressed.

Among recent incidents, the Australian Defense Department said in June that a Chinese fighter jet had dangerously intercepted one of its maritime surveillance planes over the South China Sea.

Having rapidly built artificial islets with military infrastructure, Beijing claims sovereignty over almost all of the South China Sea. Its territorial claims in the area overlap with four of the 10 countries that make up the Association of Southeast Asian Nations -- Brunei, Malaysia, the Philippines and Vietnam -- as well as Taiwan.

Ratner said China had escalated tensions with its neighbors in the waters "at a pace unseen before," employing its military, maritime militia and state-owned enterprises to "intimidate and impose its preferences on regional states."

He touched on an incident earlier this year in which the China Coast Guard is alleged to have aggressively approached Vietnamese drilling vessels engaged in energy-exploration activities within Vietnam's exclusive economic zone.

"So these actions...are not individual provocations. Beijing is systematically testing the limits of our collective resolve and advancing a new status quo in the South China Sea," the official said at the event, organized by the Center for Strategic and International Studies.

Related coverage:

Biden says will speak with China's Xi in next 10 days

U.S. airs concern about China-Russia alignment amid Ukraine war

U.S. import ban over China's forced labor in Xinjiang takes effect