Donald Trump spoke with Taiwan President Tsai Ing-wen last week, marking the first time in nearly 40 years that a U.S. leader has had a public conversation with a Taiwanese counterpart.

The call upended decades of diplomatic practice, prompting some experts to question whether Trump would deviate from America’s longstanding One China policy, which recognizes Taiwan as part of China.

Beijing filed a complaint with the State Department. And the People’s Daily, China’s official newspaper, admonished Trump for speaking with Tsai. But others, like Trump’s former economic adviser Stephen Moore, defended his former boss’ phone call. “Taiwan is our ally,” he said in a radio interview. “We ought to back our ally, and if China doesn’t like it, screw ’em.”

We asked Suzanne Ogden, China specialist and professor emeritus in the Department of Political Science, to discuss the global implications of Trump’s historic Taiwan call.

First and foremost, what are the signals Trump is trying to send to China by taking a phone call from Taiwan’s president? Is it possible for Trump to take a hard line with China, as he repeatedly promised on the campaign trail, while still adhering to the One China policy?

At the outset, I can say with assurance that there is nobody inside the Washington Beltway, and perhaps no one inside Trump Tower, who knows what President-elect Trump’s intentions are vis-à-vis China. But Trump will find out quickly that our relationship with China is deep, broad, and complex. China has enormous bargaining power in this relationship, and it is difficult to imagine that China will accept any change in the One China policy. China has long held that Taiwan is part of China and not a sovereign state. Taiwan is a key part of its “core interest” and China is unlikely ever to let Taiwan become independent.

China has its own hard line and could easily retaliate against any measure that undermines the One China policy with severe counter-measures damaging to the US. Perhaps China would accept some softening of the severe isolation of Taiwan if it could see it as in China’s own interests, but Beijing legitimately fears that even small steps down this path could lead to problems in its ultimately integrating Taiwan under mainland control.

Earlier this week it was revealed that former Sen. Bob Dole was paid nearly $150,000 by the Taiwanese government to foster a relationship between Trump and Taiwan. According to a report in The New York Times, this suggests that Trump’s decision to take the call from Tsai “was less a ham-handed diplomatic gaffe and more the result of a well-orchestrated plan by Taiwan to use the election of a new president to deepen its relationship with the United States.” In your opinion, what does Taiwan hope to gain by currying favor with Trump?

In 1979, the quid pro quo for the U.S. to establish diplomatic relations with the People’s Republic of China was in essence to agree that there was only “one China,” not “two Chinas” or “one China, one Taiwan.” It was not possible to have diplomatic relations with the PRC without accepting this principle. Virtually all international organizations recognized the PRC  as the legitimate representative of “China.” As a result, the “Republic of China”—that is, Taiwan—which since 1950, with its small island population of fewer than 20 million, had claimed to represent the 600 million people of the China mainland, was replaced as the legitimate representative of China, leading thereafter to the diplomatic and international isolation of Taiwan.

While Taiwan’s president, Tsai Ing-wen, has no illusions that Taiwan could declare independence as a sovereign state and not suffer from a military response from the mainland, she may well think that with Trump becoming president, U.S. foreign policy will be in flux, perhaps even confusion. Trump has not accepted any briefings from the State Department and has shown little knowledge of the complexities of foreign policy; so it can be said with near certitude that when he accepted that phone call, he had no idea what the consequences might be for U.S.-China relations. And perhaps Taiwan’s president knew this.

China is the United States’ No. 1 trading partner. The two countries have cooperated effectively on climate change and the Iran nuclear deal. And the U.S. might need China’s help to halt North Korea’s nuclear program. How might strained ties between the U.S. and China affect these and other diplomatic initiatives going forward? What are the potential dangers for the U.S. if the Trump administration continues to provoke China?

As noted above, it would be unwise on the part of the Trump administration to provoke China on the One China policy without considering the deeply complex and intertwined relationship the U.S. has with China. While news stories tend to feature the negatives in that relationship, such as on human rights, Tibet, and “taking American jobs,” overall the U.S. and China are in a highly cooperative relationship. It is a “non-zero sum” game, in which we both can win or lose together.

Both sides value stability, not just in Asia, but also throughout the world. Stability is crucial both for trade and for economic development. China has worked with the U.S. on countless issues. A disruption of this very positive cooperative relationship might well undermine stability in Asia. It might even lead to a trade war, or to a very dangerous arms race, and even to conflict. When Trump is president, he will hopefully realize quickly that every action he takes will have a reaction. International affairs are like a chess game, and rarely does one move result in a checkmate.