While China's statements over House Speaker Nancy Pelosi's possible trip to Taiwan do not stray too far from what it has been saying for decades, insiders in Beijing and Washington worry that they are not empty threats.
"It's a tough call for the administration," said Michael Green of the Center for Strategic and International Studies in Washington, who helped shape Asia policy as a senior official in the George W. Bush administration.
"If they pressure Pelosi to back down, they will invite greater Chinese threats and pressure in the future and increase the odds of a crisis again down the road," he said. However, he said, "if they support her going, they risk escalating tensions in the Taiwan Strait."
"They've got to find an elegant resolution," he added.
The spiraling controversy over Pelosi's trip, which has not been confirmed by her office, has created a dilemma for both the U.S. and China amid already strained relations and growing alarm in Washington over the fate of Taiwan, a self-ruling democracy of 24 million people that Beijing claims as its territory.
Chinese leader Xi Jinping has not ruled out the use of force to achieve "reunification." Although there are no signs of an imminent invasion, China has been ratcheting up its military activity around the island, and it claims sovereignty over the entire Taiwan Strait, which U.S. warships often transit through.
Top U.S. military officials say that in the past five years, the Chinese military has grown more aggressive not just around Taiwan, but also throughout the broader region. Beijing denies the charge, pointing instead to Washington's own more frequent military activities "on China's doorstep."
Since the news broke that Pelosi might be planning a trip to the island, Chinese officials and state media have been characteristically vehement in their opposition, repeating warnings over what they see as foreign interference in the Taiwan issue.
"Should the U.S. side insist on making the visit, China will act strongly to resolutely respond to it and take countermeasures," a Chinese Foreign Ministry spokesman said, arguing that the speaker's visit would send the wrong message to advocates of independence for the island. "We will do what we say."