U.S. stocks extended declines Friday after President Donald Trump unleashed a torrent of comment on social media that suggested there was "no rush" to reach a trade agreement with China just after after he opted to increased tariffs on $200 billion worth imports in the latest escalation of the ongoing trade war.

Trump again intimated -- incorrectly -- that China would pay the cost of the tariff increases, which rose to 25% from 10% at midnight last night on around 5,700 different goods, and repeated his threat to apply levies to a further $325 billion of Chinese imports. 

Tariffs will bring in FAR MORE wealth to our country than even a phenomenal deal of the traditional kind. Also, much easier & quicker to do. Our Farmers will do better, faster, and starving nations can now be helped. Waivers on some products will be granted, or go to new source!

— Donald J. Trump (@realDonaldTrump) May 10, 2019

The comments took the air out of early gains for U.S. stocks, which had followed a global market rally built on hopes that the new tariffs, which won't apply to goods that are already in transit, would effectively create a two-week during which the two sides can reach a comprehensive agreement that could roll back last night's increase.

The Dow Jones Industrial Average fell 340 points at the start of trading, taking its week-to-date decline past 3.8%, while the S&P 500 fell 42.4 points to take its week's decline to around 4%.

....The process has begun to place additional Tariffs at 25% on the remaining 325 Billion Dollars. The U.S. only sells China approximately 100 Billion Dollars of goods & products, a very big imbalance. With the over 100 Billion Dollars in Tariffs that we take in, we will buy.....

— Donald J. Trump (@realDonaldTrump) May 10, 2019

Apple Inc. (AAPL - Get Report) was a standout decliner, falling 3% to $193.91 as investors worried that the world's biggest tech company could find itself a target of Beijing reprisals to Trump's decision on tariffs, given it reliance on both Asia supply chains and China's domestic market for 20% of its revenues.

Uber Technologies (UBER)  debuted on the New York Stock Exchange, after raising just over $8 billion from its much-anticipated initial public offering that values the ride-sharing group at $82.4 billion, against a volatile market backdrop and ongoing controversy over its business practices.

Uber shares were indicated at $42.00 to $43.00 each after it priced its offering at $45 per share, near the bottom of the $44 to $50 range its Wall Street advisors had marketed the stock to investors in the weeks prior to today's listing.

The IPO will be the biggest for a U.S.-based company since Facebook's Inc. (FB - Get Report) flotation in 2012. The 180 million shares will earn Uber $8.1 billion -- an amount that nearly matches the ride-sharing group's losses over the past three years -- and gives it a market value of $82.4 billion.

China's Commerce Ministry vowed retaliation to the new tariffs, saying in a statement Friday that unspecified countermeasures would be deployed following the "disappointing" U.S. decision, but the two-week window, as well as the fact that Vice Premier Liu He remains in Washington for a second day of talks with top U.S. trade officials, gave global markets a chance to rebound from a week of notable losses in markets around the world.

European stocks opened the Friday session on solid footing, as well, boosted by hopes that the two-week tariff window will pave the way for a U.S.-China trade deal as well as a stronger-than-expected reading of March exports from Germany that suggests surprising resilience for the region's biggest economy.

The Stoxx 600 benchmark was seen 0.6% higher by early afternoon trading in Frankfurt , with Germany's DAX performance index pacing the advance with a 0.7% gain as trade-sensitive sectors such as autos and tech lead gainers on the benchmark.

Britain's FTSE 100 was also on the move, rising 0.6% as the pound held at the 1.30 market against a moderately weaker U.S. dollar and first quarter GDP was revised up to a 0.5% growth rate.

Broader Asia stocks including China's Shanghai Composite, booked strong gains, with the benchmark rising 3.1% thanks to a late-session rally and the MSCI Asia ex-Japan index rising 0.52%.

Japan's Nikkei 225, however, was left out of the Friday rally, with the benchmark ending its worst week of the year with a 0.27% decline as the yen gained in safe-haven trading sparked by the second short-range missile test by North Korea of the past ten days.

Global oil prices were also boosted by the near-term optimism, rising across the board despite this week's EIA data showing both a bigger-than-expected reduction in domestic crude supplies and record production rates of 12.3 million barrels per day.

Brent crude contracts for July delivery, the global benchmark for oil prices, were marked 58 cents higher from their Thursday close in New York and changing hands at $70.97 per barrel while WTI contracts for June delivery were seen 46 cents higher at $62.16 per barrel.