President-elect Donald J. Trump's telephone call with Taiwan President Tsai Ing-wen on December 2, 2016, and subsequent Tweets, broke precedent. No previous U.S. president or president-elect is known to have spoken directly to a president of Taiwan, which officially calls itself the Republic of China (ROC), since the United States broke diplomatic relations with the ROC and established diplomatic relations with the People's Republic of China (PRC) on January 1, 1979. The call has raised questions about whether Trump was simply taking "a very modest step toward providing Taiwan with some measure of dignity, respect and reassurance," or whether the call may presage a drive for greater "officiality" in the unofficial U.S. relationship with Taiwan. Some analysts believe the latter could risk precipitating a crisis with the PRC, which claims sovereignty over Taiwan, an island democracy of 23.5 million people. The PRC has vowed to use force if necessary to prevent Taiwan's "secession."

Commitments the United States made to Beijing and Taipei between 1972 and 1982 underpin the U.S.-PRC and U.S.-Taiwan relationships. In a December 1978 joint communiqué with the PRC, one of three such U.S.-PRC communiqués, the Carter Administration pledged that the United States would henceforth maintain only "cultural, commercial, and other unofficial relations with the people of Taiwan" (emphasis added). The communiqué also stated that the United States "acknowledges the Chinese position that there is but one China and Taiwan is part of China." At the time, Taiwan's government agreed that Taiwan was part of China, but considered itself, not the PRC, the legitimate government of that China. Today, Taiwan's President Tsai declines to endorse the notion that Taiwan is part of China, although she does not expressly refute it.

Other U.S. commitments are contained in the 1979 Taiwan Relations Act (TRA) (P.L. 96-8). The TRA states that it is U.S. policy "to maintain the capacity of the United States to resist any resort to force or other forms of coercion" against Taiwan. It also states that United States "will make available to Taiwan such defense articles and defense services in such quantity as may be necessary to enable Taiwan to maintain a sufficient self-defense capability." Through successive administrations, the United States has repeated its commitment to its "One-China policy based on the Three Joint Communiqués and the Taiwan Relations Act," an ambiguous formula that many analysts credit with having, for close to four decades, helped keep the peace across the Taiwan Strait.

What it means to have an "unofficial" relationship has always been contested, however. Particularly since Taiwan began democratizing in the late 1980s, some observers have questioned whether the Executive Branch has taken too conservative a view of what sorts of protocols are appropriate for an "unofficial" relationship. Critics have often focused on self-imposed U.S. restrictions on contacts with Taiwan officials. The highest-level officials whom the United States permits to visit Taiwan, for example, are Cabinet-level officials with an economic or technical portfolio. One U.S. official of such rank has visited Taiwan in the last 16 years.

Defenders of restrictions on contacts point to the turmoil in the U.S.-PRC relationship set off by a private visit to the United States by then-Taiwan President Lee Teng-hui in 1995. Facing overwhelming support for the trip in the 104^th Congress, the Clinton Administration allowed Lee to travel to Ithaca, NY, and deliver a public speech. The PRC read the trip as showing U.S. support for Lee's alleged effort to win Taiwan's "independence" from China. The PRC carried out military exercises near the island over a period of months, culminating in March 1996 with missile launches into the waters near Taiwan's biggest commercial ports. The 1995-1996 Taiwan Strait Crisis, "the closest the United States and China had come to a crisis since the early 1960s," ended with the Clinton Administration ordering two aircraft carrier groups to the area.

Since 1996, the United States has restricted Taiwan presidents to low-profile transit visits of the United States and not permitted them to meet with Executive Branch officials while on U.S. soil. In other areas, however, the United States has at times modestly adjusted the terms of the "unofficial" relationship without causing apparent lasting damage to the U.S.-PRC relationship.

• After the 1995-1996 Taiwan Strait Crisis, the United States expanded the military relationship with Taiwan, moving from a narrow focus on arms sales to a relationship that now encompasses a dozen different security dialogues and training and military education opportunities for Taiwan military personnel. The United States also offers Taiwan assessments of Taiwan's military capabilities and procurement needs.
• With the Foreign Relations Authorization Act for FY2003 (P.L. 107-228), Congress ended the requirement that U.S. government personnel temporarily leave government service to work at the American Institute in Taiwan, the non-profit corporation through which the United States conducts its unofficial relations with Taiwan.
• In 2013, the United States and Taiwan signed a new Agreement on Privileges, Exemptions and Immunities, for the first time giving Taiwan representatives in the United States privileges and immunities similar to those enjoyed by diplomats from countries with which the United States has official relations.

The 114^th Congress passed the National Defense Authorization Act for FY2017 (S. 2943) with a sense of Congress provision that seeks to change the terms of the unofficial relationship further. Section 1284 calls for exchanges between senior U.S. and Taiwan military officers and defense officials, including U.S. general or flag officers. The provision challenges a self-imposed U.S. rule barring general or flag officers from traveling to Taiwan. How the PRC might react to such a change is uncertain.

In the wake of the Trump-Tsai call, some commentators have advocated jettisoning unofficiality altogether and re-establishing diplomatic relations with Taiwan. With Trump still, for now, a private citizen, and with his ultimate intentions toward Taiwan still unknown, however, the PRC's immediate response to the Trump-Tsai call was muted. Its Foreign Minister described the call as "a little trick played by Taiwan," and said, "I don't think it will change the one-China policy of the U.S. government.... "