The United States is “opening fire” on the world with its threatened tariffs, China warned on Thursday, saying it will respond the instant U.S. measures go into effect as the two countries locked horns in a bitter trade dispute.

After months of threats and dwindling hopes the two sides would pull back from the brink of all-out trade war, steep US tariffs on tens of billions in Chinese goods.

China already has announced it will respond in kind on the same schedule as the United States while President Donald Trump has countered with a threat to double down by progressively ratcheting US penalties up to a total of $450 billion in goods -- which would represent the lion s share of all of China s exports to the United States.

Trump's escalating global trade dispute has already affected the economy, with punitive duties now in place for steel and aluminum and the White House threatening slap duties on auto imports.

Prices are rising, especially for steel and aluminum, and companies are starting to feel reticent about investments or plan to shift production overseas to avoid retaliation against US exports.

Trump says the measures are aimed at leveling the playing field for American companies, which he says will become more competitive.

But for firms like Mid-Continent Nail Corporation in Missouri, the largest US nail manufacturer, rising steel prices have meant immediate job losses and threaten to force the company to shut down operations altogether.

Trump initially threatened to hit China with 25 percent tariffs on a list of goods worth $50 billion annually, over what Washington says is the rampant theft of US technical know-how.

But the list was pared down to 818 product categories worth more than $32 billion after US companies requested exemptions for key imports.

Economists have for months warned of the potential damage to the US and global economies from aggressive trade policies that evolve into protectionism, which would raise prices and upend global supply chains.