After Trump pledge, top White House official says China auto tariffs 'must be reduced'

White House trade adviser Peter Navarro on Monday did not confirm whether China agreed to reduce tariffs on imported automobiles, which President TrumpDonald John TrumpJoint Chiefs chairman denies report that US is planning to keep 1K troops in Syria Kansas Department of Transportation calls Trump 'delusional communist' on Twitter Trump has privately voiced skepticism about driverless cars: report MORE cited as a key concession made by Beijing in a trade ceasefire.

"That certainly came up as well in discussions," Navarro said on NPR when asked about Trump's claim. "So, that's just one of the many tariffs that have to be reduced."

Trump tweeted Sunday night following his meeting with Chinese President Xi Jinping that "China has agreed to reduce and remove tariffs on cars coming into China from the U.S. Currently the tariff is 40%."

But Chinese officials did not mention auto tariffs as a component of the truce the two leaders agreed to at the Group of 20 summit over the weekend, fueling confusion about what exactly they agreed to during the talks.

Navarro, an outspoken China hawk, foreshadowed a tough negotiation ahead, despite Trump's triumphant tone about the trade agreement.

He said U.S. Trade Representative Robert LighthizerRobert (Bob) Emmet LighthizerTrump says no discussion of extending deadline in Chinese trade talks McConnell urges GOP senators to call Trump about tariffs Companies brace for trade war MORE — a longtime critic of Chinese trade practices — would lead talks with Beijing to address significant irritants, such as forced technology transfers and trade barriers.

Treasury Secretary Steven MnuchinSteven Terner MnuchinOn The Money: Trump issues first veto, warning of 'reckless' resolution | US hits Russia with new sanctions | Dems renew push for contractor back pay | Lawmakers seek probe into undocumented workers at Trump businesses Deripaska sues Trump admin over Russia sanctions US announces new Russia sanctions with Canada, EU MORE, a free trader, has overseen the U.S.-China economic relationship under Trump. 

Navarro said China presented U.S. officials with "very, very specific" responses to 142 demands the Trump administration made on trade.

But he said U.S. tariffs on $250 billion of Chinese goods will "go up to 25 percent" if Beijing does not agree to significant changes in the next three months.

Trump agreed to hold off on that increase in exchange for Chinese promises to purchase more U.S. agricultural products and address the trade imbalance between the two nations.

Trump is touting the 90-day pause in tariff increases as a major victory in his long-running trade dispute with Xi, calling it a "BIG leap forward" — a phrase that evoked a 1950s-era Communist program that left millions dead in China.

Stock markets surged early Monday on the news that the world's two largest economies agreed to not escalate their trade conflict, for now.

But the agreement left many fundamental issues unresolved.