In a manner that is both exciting and disquieting, the new U.S. administration seems serious about rethinking almost everything in U.S.-China relationship: trade, investment, the South China Sea, and, especially, the One China policy. President-elect Trump has repeatedly told the media that “everything” is on the table, including the “One China” policy. Trump is not (at least on this issue) making a misstatement. This looks a like a real policy shift by the new president, and one that would represent the biggest change in US-China policy since President Nixon’s historic 1972 visit.

In this brief post, I will avoid discussion of the wisdom of such a shift (I will simply note that discussions during my recent trip to China suggest to me that the Chinese will not take such a shift well). But I want to focus here on the legality, both domestic and international, of U.S. abandonment of the One China policy in favor of some form of increased support or even recognition of Taiwan. My unsurprising conclusion: Neither U.S. nor international law prevents President Trump from abandoning the One China policy, recognizing Taiwan as a separate country, and even stationing U.S. troops and military assets there.

Put another way, China should probably take President-elect Trump’s threats on “One China” seriously because he has all of the legal authority he needs to carry out this seismic policy shift.

Under U.S. law, President Trump has complete constitutional discretion over whether to recognize a foreign government, and even whether to recognize a foreign government’s territorial and sovereign claims. The U.S. Supreme Court confirmed that Congress cannot restrict this power in the 2015 decision Zivotofsky v. Kerry. In that decision, the Court held that the President has the “exclusive” power to withhold recognition of Jerusalem as Israel’s capital, and that this power even extends to refusing to print passports with the designation of “Jerusalem, Israel.” The holding of Zivotofsky was not particularly controversial and would plainly govern any attempt to challenge a decision by President Trump to extend US recognition to the Republic of China (Taiwan’s formal legal name).

Similarly, the President has broad powers as Commander in Chief to direct the movement of U.S. troops and military assets as he sees fit. These powers may not be quite a “exclusive” as his recognition power, but they are close. In any event, there seems little doubt that the President could legally agree to a basing agreement with Taiwan of the type proposed by former U.S. U.N. Ambassador John Bolton in today’s WSJ. It is not clear if the President could give a defense guarantee without a treaty, but he could certainly place the troops there and order them to defend Taiwan in case of Chinese armed attack.

Under international law, the question of recognizing Taiwan is a little trickier. To be sure, the U.S. could simply join (or re-join) the dwindling number of states that recognize Taiwan. This would not violate the international law of statehood (such as it is) since Taiwan has all of the characteristics of a state under the Montevideo Convention.

The main international legal obstacle to U.S. recognition of Taiwan and basing military troops there is that the U.S. has sort-of promised China it wouldn’t do either of these things. In the 1972 Shanghai Communique that launched the re-establishment of U.S.-China relations, the U.S. “acknowledged that all Chinese on either side of the Taiwan Strait maintain there is but one China and that Taiwan is a part of China. The United States Government does not challenge that position.” To be sure, as John Bolton argued in his op-ed, the first sentence merely “acknowledges” a position that the Chinese in Taiwan probably do not agree with today. But the second sentence is more troubling. If the U.S. does not “challenge” the One China position, doesn’t that mean the U.S. accepts it? It is certainly a plausible reading of this language. This position seems even stronger if one reads the 1982 Joint Communique, which states that the U.S. “has no intention of infringing on Chinese sovereignty and territorial integrity, or interfering in China's internal affairs, or pursuing a policy of "two Chinas" or "one China, one Taiwan.” And then it is followed by subsequent administrations’ statements openly opposing Taiwanese independence.

Similarly, the U.S. went on in the Shanghai Communique to “affirm[] the ultimate objective of the withdrawal of all U.S. forces and military installations from Taiwan. In the meantime, it will progressively reduce its forces and military installations on Taiwan as the tension in the area diminishes.” It did, in fact, remove all U.S. military forces before U.S. normalization of diplomatic relations in 1979.

I think a fair reading of these various “communiques” is that the U.S. promised that it would follow a policy of “One China” and withhold recognition of Taiwan as a separate country. It also (less clearly) agreed to work to remove all of its military forces from Taiwan, although it did not make such a promise never to put them back. Still, in my view, none of these promises are legally binding under international law.

At various times Chinese leaders and government spokesmen have referred to these communiques as binding international agreements. I think most lawyers, however, would treat these joint statements as nonbinding “political commitments” that merely express diplomatic intentions but do not represent a formal agreement under international law. Most such joint statements with lots of nonbinding language involving future “intentions” for “progressive reduction” and “acknowledging” facts would not be seen as legally binding international agreements.

In any event, it is clear that the President has broad authority under U.S. law to withdraw from even binding international legal commitments. He certainly would have no problem withdrawing from binding ones like the Three U.S.-China Communiques. I don’t think the Taiwan Relations Act requires him to do so, but it certainly suggests Congress does not want to stop the President from supporting Taiwan.

U.S.-China policy has always depended on the interests of the two countries in maintaining strong relations and cooperation despite sensitive questions like Taiwan. The legal framework for this relationship is surprisingly thin, however, and any new U.S. president is always empowered to completely change it should he choose to. A shift along the lines outlined by Trump or Bolton may be unwise, and it could even lead to a shooting war, but it is one of the many important powers President-elect Trump will assume on January 20. China should be prepared.