iStock/Thinkstock(WASHINGTON) — President-elect Donald Trump’s unprecedented phone call with the leader of Taiwan on Friday, followed by his anti-China tweets on Sunday, signal strongly that upon taking office next month he could seek to deviate further from America’s long-standing “One-China” policy.

Trump’s phone call with Taiwanese President Tsai Ing-wen on Friday (which he says was initiated by Taiwan) prompted headlines across the U.S. that Trump had broken with decades-old policy and even forced the White House to respond and affirm its commitment to current policy.

Secretary of State John Kerry even said over the weekend that it “would be helpful” if the president-elect’s transition team consulted with the State Department before speaking with foreign leaders.

So, what is the U.S. position on China and Taiwan and why exactly is it so delicate?

One China, Briefly

Since the signing of the Taiwan Relations Act in 1979, it’s been the official policy of the United States to recognize Taiwan as part of China.

“The United States does not support Taiwan independence,” reads the State Department’s own fact sheet updated just this past September. But, it goes on, “maintaining strong, unofficial relations with Taiwan is a major U.S. goal, in line with the U.S. desire to further peace and stability in Asia.”

In fact, Taiwan is the United States’ ninth-largest trading partner, and according to State Department figures, Taiwan employed more than 12,000 workers in the United States and paid them nearly $1 billion. The One China policy amounts to a delicate balance between respecting China’s claim to its territory and maintaining close ties to Taiwan.

Missiles Pointed

The U.S. commitment to Taiwan also permits the sale of defensive weapons, and just last year the U.S. sold Taiwan $1.83 billion worth of them, most of which Taipei uses to defend itself from a potential provocations from Beijing.

That last package, the first of its kind in four years, included two Oliver Hazard Perry class Navy frigates, Javelin anti-tank missiles, amphibious assault vehicles, anti-aircraft missiles, and anti-ship systems, among other things.

Since 1979, the U.S. carried out $12 billion in weapons sales to Taiwan, and Beijing voices its opposition every time.

David McKeeby, at spokesman in the State Department’s bureau of political-military affairs, told ABC News Monday that the U.S is constantly reviewing Taiwan’s defensive needs and requests and will continue to do so. “We do not consult Beijing about our military cooperation with or arms sales to Taiwan,” McKeeby said.

Despite the weapons sales and the importance of good relations emphasized by both sides, Taiwan is not a treaty ally with the United States and the U.S. has no obligation to defend it in the event it were ever attacked.

Trump’s Approach

ABC News learned Monday that Trump’s congratulatory call from the president of Taiwan last week was expected and likely pre-arranged by people in his transition team. So, while it was a surprise to China and many in the United States government, Trump’s advisers are claiming it was calculated.

Trump took a firm stance towards confronting a rising China during his campaign, repeatedly accusing China of manipulating its currency and once claiming “we already have a trade war [with China],” suggesting he doesn’t fear an escalation.

He’s also floated the idea of imposing major tariffs on Chinese products. “We have the power over China, economic power, and people don’t understand it,” Trump said in April.

He also opposes the Trans Pacific Partnership, which effectively leaves the future trade relationship with China undecided.

Did China ask us if it was OK to devalue their currency (making it hard for our companies to compete), heavily tax our products going into..

— Donald J. Trump (@realDonaldTrump) December 4, 2016

their country (the U.S. doesn’t tax them) or to build a massive military complex in the middle of the South China Sea? I don’t think so!

— Donald J. Trump (@realDonaldTrump) December 4, 2016

China’s Response

The Chinese government has yet to issue a public rebuke of the phone call, but the Foreign Ministry spokesman told reporters Monday that Beijing has been in contact with Trump’s team since the call and suggested that it made its concerns known directly.

However, the Foreign Ministry does not wield the same power as the party leadership and a more meaningful reaction would come from that office or from the Chinese military.

Those bodies might not offer a response until Trump is actually in office and dictating policy.

China’s state owned English newspaper, the China Daily, published an editorial on Saturday saying “for Trump, it exposed nothing but his and his transition team’s inexperience in dealing with foreign affairs.”

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