(Reuters) - Top U.S. and Chinese trade officials met on Thursday for the first time since late July to try to find their way out of a bitter, 15-month trade war as new irritants between the world’s two largest economies threatened to dash hopes for progress.

Chinese Vice Premier Liu He, U.S. Trade Representative Robert Lighthizer and Treasury Secretary Steven Mnuchin were trying to narrow differences enough to avoid a scheduled Oct. 15 tariff rate increase on $250 billion worth of Chinese goods.

But the atmosphere surrounding the talks was soured by the U.S. Commerce Department’s decision on Monday to blacklist 28 Chinese technology and surveillance firms, citing human rights violations of Muslim minority groups in China’s Xinjiang province.

A day later, the U.S. State Department imposed visa restrictions on Chinese officials related to the Xinjiang issue.

If talks fail to produce progress, by Dec. 15, nearly all Chinese goods imports into the United States -- more than $500 billion -- could be subject to punitive tariffs in the dispute, which spans U.S. President Donald Trump’s entire time in office. Tariffs would be applied to nearly all US goods imported into China as well.

The following timeline details key moments in the souring trade relationship between the world’s two largest economies.

June 28, 2016

S&P 500: +1.78%

While campaigning for the White House, Trump lays out plans to counter unfair trade practices from China at a rally in Pennsylvania. He also previews his eventual moves to apply tariffs under sections 201 and 301 of the Trade Act of 1974. He says China’s entrance into the World Trade Organization enabled the “greatest jobs theft in history.”

March 31, 2017

S&P 500: -0.23%

Trump, now president, signs two executive orders. One calls for tighter tariff enforcement in anti-subsidy and anti-dumping trade cases. The other orders a review of U.S. trade deficits and their causes.

April 7, 2017

S&P 500: -0.08%

At their first meeting at Trump’s Mar-a-Lago estate in Florida, Trump and Chinese President Xi Jinping agree to a 100-day plan for trade talks.

July 19, 2017

S&P 500: +0.54%

The two sides fail to agree on new steps to reduce the U.S. deficit with China after the 100 days of talks.

Aug. 14, 2017

S&P 500: +1.00%

Trump orders “Section 301” probe into alleged Chinese intellectual property theft, described as his first direct trade measure against Beijing.

Jan. 17, 2018

S&P 500: +0.94%

Trump, in a Reuters interview, threatens a big “fine” on China over alleged IP theft, without providing details.

Jan. 22, 2018

S&P 500: +0.81%

Trump imposes tariffs on all imported washing machines and solar panels - not just those from China.

March 8, 2018

S&P 500: +0.45%

Trump orders 25% tariffs on steel imports and 10% on aluminum from all suppliers - not just China.

April 2, 2018

S&P 500: -2.23%

China imposes tariffs of up to 25% on 128 U.S. products.

April 3, 2018

S&P 500: +1.26%

Trump unveils plans for 25% tariffs on about $50 billion of Chinese imports.

April 4, 2018

U.S. Treasury Secretary Steve Mnuchin (R) and Trade Representative Robert Lighthizer wait to welcome China's Vice Premier Liu He before the two countries' trade negotiations in Washington, U.S., October 10, 2019. REUTERS/Yuri Gripas

S&P 500: +1.16%

China responds with plans for retaliatory tariffs on about $50 billion of U.S. imports.

June 15, 2018

S&P 500: -0.10%

The United States sets an effective date of July 6 for 25% levies on $34 billion of Chinese imports. It says 25% tariffs will also kick in on an additional $16 billion of goods after a public comment period. China responds in kind with tariffs on $34 billion of U.S. goods.

July 10, 2018

S&P 500: +0.35%

The United States unveils plans for 10% tariffs on $200 billion of Chinese imports.

Aug. 1, 2018

S&P 500: -0.10%

Trump orders USTR to increase the tariffs on $200 billion of Chinese imports to 25% from the originally proposed 10%.

Aug. 7, 2018

S&P 500: +0.28%

The United States releases the list of $16 billion of Chinese goods to be subject to 25% tariffs. China retaliates with 25% duties on $16 billion of U.S. goods.

Aug. 23, 2018

S&P 500: -0.17%

Tariffs on goods appearing on the Aug. 7 lists from both the United States and China take effect.

Sept. 7, 2018

S&P 500: -0.22%

Trump threatens tariffs on $267 billion more of Chinese imports.

Sept. 24, 2018

S&P 500: -0.35%

The United States implements 10% tariffs on $200 billion of Chinese imports. The administration says the rate will increase to 25% on Jan. 1, 2019. China answers with duties of its own on $60 billion of U.S. goods.

Dec. 1, 2018

S&P 500: +1.09% (Monday, Dec. 3)

The United States and China agree on a 90-day halt to new tariffs. Trump agrees to put off the Jan. 1 scheduled increase on tariffs on $200 billion of Chinese goods until early March while talks between the two countries take place. China agrees to buy a “very substantial” amount of U.S. products.

Feb. 24, 2019

S&P 500: +0.12% (Monday, Feb 25)

Trump extends the March 1 deadline, leaving the tariffs on $200 billion of Chinese goods at 10% on an open-ended basis.

May 5, 2019

S&P 500: -0.45% (Monday, May 6)

Trump tweets that he intends to raise the tariffs rate on $200 billion of Chinese goods to 25% on May 10.

May 8, 2019

S&P 500: -0.16%

The Trump administration gives formal notice of its intent to raise tariffs on $200 billion of Chinese imports to 25% from 10%, effective May 10.

Earlier, Reuters reported that China had backtracked on almost all aspects of a draft U.S.-China trade pact.

June 18, 2019

S&P 500: +0.97%

Trump and Xi speak by phone, and the two sides agree to rekindle trade talks ahead of a planned meeting between the two leaders scheduled for the Group of 20 (G20) summit in Japan at the end of June.

June 29, 2019

S&P 500: +0.77% (Monday, July 1)

At the G20 meeting in Osaka, the United States and China formally agree to restart trade talks after concessions from both sides. Trump agrees to no new tariffs and an easing of restrictions on Chinese telecom powerhouse Huawei Technologies Co Ltd [HWT.UL]. China agrees to unspecified new purchases of U.S. farm products.

Aug. 1, 2019

S&P 500: -0.90%

After two days of trade talks with no visible progress and complaints by Trump that China has failed to keep a promise to buy more U.S. farm products, he announces 10% tariffs on $300 billion worth of Chinese imports, in addition to the 25% already levied on $250 billion worth of Chinese goods.

Aug. 5, 2019

S&P 500: -2.98%

China’s Commerce Ministry responds to the latest U.S. tariffs by halting purchases of U.S. agricultural products, and the Chinese currency, the yuan, weakens past the key seven per dollar level, sending equity markets sharply lower.

After U.S. markets close, the U.S. Treasury says it has determined for the first time since 1994 that China is manipulating its currency, knocking the U.S. dollar sharply lower and sending gold prices to a six-year high.

Aug. 13, 2019

S&P500: +1.5%

Trump delays more than half of his 10% tariffs on the $300 billion goods list until Dec. 15, sparing cell phones, laptop computers, toys and other major consumer categories from immediate tariffs. He says this was to avoid pain for consumers and retailers during the Christmas selling season. But 10% tariffs on about $125 billion worth of other Chinese goods, including smart speakers, bluetooth headphones and many types of footwear, take effect on Sept. 1

Aug. 23, 2019

S&P 500: -0.1%

China announces it will impose additional retaliatory tariffs against about $75 billion worth of U.S. goods, putting as much as an extra 10% on top of existing rates in response to the U.S. tariffs announced earlier in August.

Sept. 20, 2019

S&P 500: -0.53%

A two-day meeting of U.S. and Chinese deputies, the first in-person talks in nearly two months, ends with Chinese officials canceling a planned visit to U.S. farming regions at the Trump administration’s request. But both sides describe the talks as “productive” and agree to keep talking.

The same day, USTR issues tariff exclusions on about 400 Chinese products, from dog collars to printed circuit boards for computer graphics processors - a move widely seen as a goodwill measure.

Sept. 23, 2019

S&P 500: -0.01%

Chinese companies the following monday buy about 600,000 tonnes of U.S. soybeans, resuming modest purchases started earlier in September that would reach 3.5 million tonnes by early October -- about 10% of China’s annual pre-trade war volumes.

Oct. 7

S&P 500: -0.46%

The U.S. Commerce Department puts 28 Chinese companies on its “entity list,” largely banning U.S. firms from selling to them, over their alleged involvement in human rights abuses against Uighur Muslims in Xinjiang. China denounces the move as interference in Chinese sovereignty. Chinese officials later say the move hurts the atmosphere surrounding trade talks.

Oct. 10

S&P 500 open: -0.066%

High level delegates from China and the U.S. meet in Washington for two days of talks.

(GRAPHIC - Flashpoints in the U.S.-China trade war: here)