National Economic Council Director Gary Cohn asked South Korean President Moon Jae-in on Friday for help in working with China.

"At some point we'd be interested to hear how you're dealing with the Chinese policies and how you could help us in dealing with Chinese policies," Cohn said in candid comments on camera because the press was invited in to view the start of the meeting.

Speaking at the request of President Donald Trump, the former Goldman Sachs president listed China's "many predatory practices," such as:

its infringement on intellectual property rights

its demand that the U.S. transfer technology into China

its requirements that U.S. firms form joint ventures with Chinese companies to operate in the country

its restrictions on U.S. ownership of companies in China.

The detailed list follows the Trump administration's tough turn this week on China. The Treasury on Thursday issued sanctions against a Chinese shipping firm and two Chinese citizens tied to North Korea. The U.S. also plans to sell Taiwan $1.42 billion in arms, Reuters reported Thursday, citing a State Department spokeswoman.

Then on Friday, Axios reported the White House is "hell-bent" on potentially imposing roughly 20 percent tariffs on imports from countries such as China.

South Korea is China's largest source of imports, and the smaller country's economy has come under significant pressure from Beijing for allowing the U.S. to deploy a missile defense system in South Korea. Although the system is intended to deflect North Korean missiles, China views it as a security threat and has boycotted and banned South Korean products.

After winning the election in early May, Moon temporarily suspended deployment of the missile defense system. Last week, Moon said he would ask Chinese President Xi Jinping to lift China's retaliatory measures against South Korean businesses. He also said China should do more to curb North Korea's nuclear weapons development.

Trump has criticized U.S. trade policies with China and South Korea. In 2016, the U.S. had a $347 billion trade deficit with China for goods and a $27.7 billion deficit with South Korea, according to the U.S. Census Bureau.

"Much of our biggest problem on trade has to do with our economic relationship with China," Cohn said. "We have maintained a very large trade deficit with China and it continues to grow."

Also Friday, Trump pledged to work with Moon on dealing with the "menace known as North Korea."

— Reuters contributed to this report.