By Ben Blanchard and Roberta Rampton
BEIJING/WASHINGTON (Reuters) - The White House said on Monday it had sought to reassure China after President-elect Donald Trump's phone call with Taiwan's leader last week, which the Obama administration warned could undermine progress in relations with Beijing.
The statement from a spokesman for U.S. President Barack Obama highlighted concerns about the potential fallout from Trump's unusual call with Taiwan President Tsai Ing-wen on Friday, which prompted a diplomatic protest from Beijing on Saturday.
White House spokesman Josh Earnest said senior National Security Council officials spoke twice with Chinese officials over the weekend to reassure them of Washington's commitment to the "One China" policy and to "reiterate and clarify the continued commitment of the United States to our longstanding China policy."
The policy has been in place for 40 years and is focused on promoting and preserving peace and stability in the strait separating China and Taiwan, which is in U.S. interests, Earnest said.
"If the president-elect's team has a different aim, I'll leave it to them to describe," he said.
"The Chinese government in Beijing placed an enormous priority on this situation, and it’s a sensitive matter. Some of the progress that we have made in our relationship with China could be undermined by this issue flaring up," he said.
Despite tensions over matters ranging from China's pursuit of territorial claims in the South China Sea and trade, the Obama administration has highlighted cooperation on global issues, such as climate change and Iran and North Korea's nuclear programs.
Earlier on Monday, China's foreign ministry said Trump was clear about China's position on the Taiwan issue and that China has maintained contacts with his team. Vice President-elect Mike Pence sought to play down the telephone conversation, saying it was a "courtesy" call, not intended to show a shift in U.S. policy on China.
Chinese foreign ministry spokesman Lu Kang would not say directly who China had lodged "stern representations" with about Trump's call, repeating a weekend statement that it had gone to the "relevant side" in the United States.
"The whole world knows about the Chinese government's position on the Taiwan issue. I think President-elect Trump and his team are also clear," Lu told a daily news briefing.
"The Chinese side in Beijing and Washington lodged solemn representations with the relevant side in the U.S."
Pressed on who the diplomatic protest was lodged with, Lu said: "I think it's easy to understand 'the relevant side.'
"In fact, China has maintained contacts and communication with the team of President-elect Trump," he added, repeating a previous assertion, though he did not give details.
Lu also said he would not speculate on what prompted the call, but described the matter of Taiwan as the most important and sensitive question between China and the United States.
Trump, who vowed during his campaign to label China a currency manipulator, issued more tough rhetoric on Sunday.
"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 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!" Trump said on Twitter.
China, Taiwan, the Philippines, Vietnam, Malaysia and Brunei claim parts or all of the energy-rich South China Sea, through which trillions of dollars in trade passes annually.
Lu would not be drawn on directly commenting on Trump's tweets but defended the China-U.S. relationship.
"The China-U.S. economic and trade relationship has over many years always been a highly mutually beneficial one, otherwise it couldn't have developed the way it has today," he said.
PHONE CALLS
The diplomatic contretemps was one of several recently for the Republican president-elect, a real estate magnate who has never held public office and has no foreign affairs or military experience.
Trump, who takes office on Jan. 20, is still considering his choice for secretary of state.
The call with Taipei was the first by a U.S. president-elect or president with a Taiwan leader since President Jimmy Carter switched diplomatic recognition to China from Taiwan in 1979, acknowledging Taiwan as part of "one China." China regards Taiwan as a renegade province.
China blamed Taiwan for the call, but also lodged the diplomatic protest with the United States, saying the "one China" policy was the bedrock of relations with the United States.
Pence called the uproar over the call with "democratically elected" Tsai a "tempest in a teapot." He blamed the media for the controversy, saying the call was similar in nature to one between Trump and Chinese President Xi Jinping after the Nov. 8 election.
"I would just say to our counterparts in China that this was a moment of courtesy. ... It was not a discussion about policy," Pence said on NBC's "Meet the Press."
Pence said he was not aware of any contact between the Trump transition team and the Chinese government since Friday and did not expect Trump's team to reach out this week to ease tension with Beijing.
U.S. Secretary of State John Kerry said on Sunday the Trump transition team had yet to contact the State Department for information and recommendations ahead of calls with foreign leaders.