Hong Kong(CNN) China is stepping up military drills around East Asia as a war of words with the United States heats up over Washington's military activities and the visit of a US cabinet secretary to Taiwan.
One Chinese think tank even says the People's Liberation Army (PLA) may consider live-fire exercises near the US island of Guam.
Beijing has stepped up the pace of its war games in recent weeks, after the US sent two aircraft carrier strike groups on rare dual-carrier exercises in the South China Sea twice in the month of July.
But the visit of US Health and Human Services Secretary Alex Azar to the self-governed island of Taiwan this week has added fuel to the smoldering tensions. Azar is the highest-ranking US official to visit the island -- which Beijing regards as Chinese territory -- in decades.
Azar's presence in Taipei is "a serious breach" of US commitments on Taiwan, Chinese Foreign Ministry spokesperson Zhao Lijian said Monday afternoon.
"We urge the US side to abide by the one-China principle and the provisions of three China-U.S. joint communiques, stop official interactions and contact of all kinds as well as the upgrading of substantive relations with the island, and handle Taiwan-related issues in a prudent and proper manner, so as not to seriously damage China-US cooperation in major areas as well as peace and stability across the Taiwan Strait," Zhao said, according to the state-run Xinhua news agency.
On Monday morning, China sent fighter jets across the median line in the Taiwan Strait, which Taiwan said its warplanes warned off. The Chinese jets were also tracked by Taiwan's land-based anti-aircraft missiles, Taiwan's Defense Ministry said.
Though still in international airspace, the Taiwan Strait median line has been an informal but largely respected dividing line for Beijing and Taipei. According to Taiwanese and US government reports, Beijing's warplanes have only crossed it intentionally three times since 1999 -- once in March 2019, in February of this year, and again on Monday.
A story from state-supported Global Times, appearing on the official English language website of the PLA, showed Beijing's displeasure with Washington over Azar's visit to Taiwan.
"The PLA operation is considered a strong response to the US move, which broke a diplomatic bottom line of China-US relations," the story said.
It goes on to say if Washington doesn't back down, more moves by the PLA may be necessary.
"If the US goes further, the PLA could take more countermeasures, including live-fire missile drills east of Taiwan island and near Guam," the story says, citing Xu Guangyu, a senior adviser to the China Arms Control and Disarmament Association.
Maj. Randy Ready, spokesman for the US Indo-Pacific Command in Hawaii, said the US military "won't speculate on hypothetical exercises that may or may not take place in the future."
The mention of possible exercises off Guam, home to the important US military installations of Andersen Air Force Base and Naval Station Guam, comes after a busy few weeks for the PLA.
"Ground and naval forces of the Chinese People's Liberation Army (PLA) have been on concentrated schedules in amphibious landing and maritime exercises in the past weeks and will continue to do so in the weeks to come," a Global Times report said.
Recent drills include a mock beach assault in Hainan province on the South China Sea; a sea-crossing and landing with amphibious assault vehicles in Guangdong province; sea-crossing assault drills in Fujian province; and flights of missile-armed bombers and fighters over the South China Sea.
The PLA has live-fire exercises planned for this week and next, according to another Global Times report.
Those drills will be off Zhoushan, an island on China's east coast south of Shanghai.
"The PLA drills come amid the increasingly frequent provocative military activities made by the US near the island of Taiwan and in waters in the South China Sea," the Global Times report says.
In a Xinhua interview, Chinese Foreign Minister Wang Yi last week accused Washington of sending 2,000 military flights over the South China Sea in the first half of this year. That would be a rate of almost 11 a day.
Ready, the Indo-Pacific command spokesman, would not confirm Wang's assertion on the number of US flights.
"There has been no significant change to our military operations in or around the South China Sea," Ready said. "Though the frequency and scope of our operations vary based on the current operating environment, the U.S. has a persistent military presence and routinely operates throughout the Indo-Pacific, including the waters and airspace surrounding the South China Sea, just as we have for more than a century."
Wang contends otherwise.
"The US keeps increasing and showing off its military presence in the South China Sea," Wang said, calling it part of a plan to "destabilize" the 1.3 million square mile region, most of which China claims as its sovereign territory and where it has been fortifying man-made islands with military facilities and equipment.
Military analyst Carl Schuster, a former director of operations at the US Pacific Command's Joint Intelligence Center, said it would not be surprising to see Chinese military exercises that make a strong statement to both Washington and Taipei.
"It is apparent from the increasing complexity of China's maritime exercises that they are working up to something," Schuster said, adding that he expects an important exercise in the fall.
"They probably will do an air-naval strike exercise east of Taiwan. If Xi (Chinese President Xi Jinping) wants to send a threat, it may include a ballistic missile launch into the waters west of Guam," Schuster said.
The fact the Guam possibility appeared in a story on the PLA's official English-language website gives it credence, he said.
"I am sure the idea is on the table since the Chinese military would not publish such bombastic rhetoric on its initiative," he said. "Someone of authority in the Communist Party or PLA feels that way and is pushing for it."
Despite all the rhetoric being played out in the media, military leaders in Washington and Beijing have been talking.
Last week, US Defense Secretary Mark Esper spoke with his Chinese counterpart, Gen. Wei Fenghe, by phone.
"Both leaders agreed on the importance of maintaining open channels of communication and developing the systems necessary for crisis communications and risk reduction," a statement from the US Defense Department said.
Wei, according to China Military Online, urged "the US side to stop wrong words and deeds, enhance maritime risk control and prevent dangerous action" that could exacerbate tensions.