The Chinese government has been working overtime to undermine U.S. interests and generally undermine the Biden administration at every turn. It’s part of a larger effort to supplant the United States as the major global power on the world stage, and the Biden administration’s seeming lack of interest in some of China’s actions is making it possible.

Tensions between Washington D.C. and Beijing are at an all-time high, and the island nation of Taiwan is at the center of some of it. The U.S. has historically been an unofficial partner of Taiwan, which China claims is a violation of their “One China” policy as they claim historic ownership of the island. But the Taiwan government has been subjected to harassment by the Chinese government in retaliation for their defiance of Chinese rule.

Amid all this, Taiwanese President Tsai Ing-wen is preparing for a meeting with House Speaker Kevin McCarthy in what the Wall Street Journal is calling “the most pivotal event in her closely watched travels through the U.S.”

Ms. Tsai is set to land in Los Angeles on Tuesday evening for the second of two multiday stopovers in the U.S. on her way to and from visiting Taiwan’s diplomatic partners in Central America. At the top of her agenda in California is a long-anticipated meeting with Mr. McCarthy in the Ronald Reagan Presidential Library on Wednesday that Beijing has warned would lead to unspecified retaliation.

Visits to the U.S. by Taiwanese leaders are labeled as “transits” and considered unofficial, part of Washington’s delicate diplomatic dance with Beijing, which considers Taiwan a part of Chinese territory. As a result, Taiwanese leaders avoid stops in Washington and typically don’t meet with senior U.S. officials.

If the meeting goes ahead as planned, the House speaker would become the highest-level U.S. official to meet a Taiwanese leader on American soil since the practice of transit visits began.

Such a meeting would “be an assault on the political foundation of Sino-U.S. relations,” a spokesperson for the Chinese Consulate in Los Angeles said Monday. “This is the first red line that must not be crossed.”

China does not like the U.S. granting legitimacy to Taiwan’s government, and the Chinese are furious at the level of cooperation between the two countries on this front. After then-Speaker Nancy Pelosi visited Taiwan, the Chinese military launched a series of “missile tests” around the island nation and generally tested its naval response.

It was the kind of maneuvering that had the U.S. worried about China’s ability to blockage Taiwan, and the fear in Washington is that the Chinese government has upped its timeline to invade Taiwan, especially given recent boosts in their military spending.

At the same time, the U.S. military has committed to upping the number of service members in Taiwan, ostensibly for training purposes, specifically on U.S. weapons systems and tactical maneuvers.

The meeting is also set the day after it was revealed that a Chinese spy balloon that flew over the nation was being directly controlled by the Chinese, as opposed to aimlessly floating as previously claimed. It was also actively transmitting information from sensitive military sites to the Chinese government.