U.S. President Donald Trump, who rattled global markets Tuesday after declaring himself 'a Tariff Man,' predicted in a series of tweets Wednesday the United States and China would negotiate a new trade deal.

Trump said China is planning to resume buying U.S. soybeans and natural gas, which he said confirms his claims that China had agreed to start 'immediately' buying U.S. products.'

Trump said he believes 'President Xi (Jinping) meant every word of what he said' at their meeting recently in Argentina, including 'his promise to me to criminalize the sale of deadly Fentanyl coming into the United States.'

The president's optimistic comments came one day after stock prices around the world plunged in response to a series of tweets he posted on Tuesday, warning a fragile accord between the two countries could crumble.

Stocks in the U.S., Europe and Asia fell sharply after Trump declared himself 'a Tariff Man' who wants 'people or countries' with intentions to 'raid the great wealth' of the U.S. 'to pay for the privilege of doing so.'

Trump and President Xi, leaders of the world's two biggest economies, agreed Saturday in Argentina to not impose any new tariffs on each other's exports for the next 90 days while they negotiate a detailed trade agreement.

White House economic adviser Larry Kudlow said earlier this week the U.S. won Chinese commitments to buy more than $1 trillion in American products.

The U.S. had a $335.4 billion trade deficit with China in 2017.

Late Sunday, Trump tweeted that 'China has agreed to reduce and remove tariffs on cars coming into China from the U.S. Currently, the tariff is at 40 percent

On Monday, Kudlow said there was an 'assumption' that China would eliminate auto tariffs, not a specific agreement.

China's ministry of foreign affairs said Monday the Chinese and U.S. president had agreed to work toward removing all tariffs.

The 90-day truce in the escalating trade war between the U.S. and China came during a dinner meeting between the two presidents following the G-20 summit of the world's industrialized and emerging economies in Buenos Aires. For months, the two countries have engaged in tit-for-tat increases in tariffs on hundreds of billions of dollars of exports flowing between the two countries.

Trump, speaking to reporters on Air Force One after the plane departed Argentina, said his agreement with Xi, will go down 'as one of the largest deals ever made... And it'll have an incredibly positive impact on farming, meaning agriculture, industrial products, computers - every type of product.'

Trump agreed he will leave the tariffs on $200 billion worth of Chinese products at 10 percent, and not raise it to 25 percent as he has threatened to do Jan. 1, according to a White House statement.

Trump and Xi also agreed to immediately begin negotiations on structural changes with respect to forced technology transfer, intellectual property protection, non-tariff barriers, cyber intrusions and cyber theft, services and agriculture, according to the White House statement.