President Donald Trump announces tariffs of 25 per cent on steel imports and 10 per cent on aluminium from many countries in a bid to slash the huge US trade deficit.
The deficit reached $566 billion in 2017, of which $375 billion was with China, the world's biggest steel and aluminium producer.
March 22: China ripostes
On the eve of their application, Trump suspends the tariffs for several countries but not China.
Beijing responds with a list of 128 US products on which it says it will impose customs duties of 15-25 per cent if negotiations with Washington fail.
July 6: Trade war
The United States nonetheless slaps 25-per cent duties on about $34 billion of Chinese imports, including cars, hard disks and aircraft parts.
Beijing imposes tariffs of equal size and scope, including on-farm produce, cars and marine products.
August 23: Escalation
Washington imposes tariffs on another $16 billion of Chinese goods on August 23, a day after negotiations resume.
China applies 25-per cent tariffs on $16 billion of US goods, including Harley-Davidson motorcycles, bourbon and orange juice.
On September 24, Washington slaps 10 per cent taxes on $200 billion of Chinese imports. Beijing puts customs duties on $60 billion of US goods.
December 1: Truce
Washington suspends for three months a tariff increase from 10 to 25 per cent due to begin January 1 on $200 billion of Chinese goods.
China agrees to purchase a "very substantial" amount of US products and suspends extra tariffs added to US-made cars and auto parts for three months starting January 1. It allows imports of American rice.
May 10, 2019: Hostilities resume
Washington ends the truce, increasing duties on $200 billion in Chinese imports.
Trump opens a new front in the war on May 15, barring US companies from using foreign telecoms equipment deemed a security risk - a move aimed at Chinese giant Huawei.
The US Commerce Department also announces an effective ban on US companies selling or transferring US technology to Huawei.
On May 20 it issues a 90-day reprieve on the ban.
May 19: Signs of appeasement
The two countries announce a draft deal under which Beijing agrees to reduce its trade surplus "significantly".
In the following weeks, China makes several conciliatory gestures, reducing customs duties, lifting restrictions and offering to buy extra US goods.
June 29: Negotiations 'back on'
At the G20 in Osaka, Trump and President Xi Jinping strike a ceasefire. Washington vows to hold off on further tariffs and Trump declares trade negotiations "back on track".
US and Chinese negotiators meet in Shanghai on July 30 and 31 for "constructive" talks and agree to continue discussions in September.
August 1: New US sanctions
Accusing Beijing of reneging on promises to buy US agricultural products and stop the sale of the opioid fentanyl, Trump announces new 10 per cent tariffs on another $300 billion in Chinese goods from September 1.
It means virtually all of the $660 billion in annual trade between the world's two biggest economies will be subject to duties.
Beijing threatens counter-measures.
August 5: Currency row
China allows the yuan to fall below 7.0 to the dollar for the first time in 11 years. Washington accuses Beijing of manipulating its currency to help its exports, a charge denied by China's central bank.
Chinese state media announced that Beijing had suspended purchases of American farm exports.