"The United States' allies in Northeast Asia will be watching closely to see if the Trump administration will stand by its friends against increasing pressure from Beijing. How Trump deals with China's massive retaliation against South Korea in response to US missile defense deployment is one crucial test," Josh Rogin, a Washington Post columnist, wrote.

Last year, South Korea decided to host a THAAD battery to boost defenses against North Korea.

China has taken a number of economic retaliatory measures, including restrictions on South Korean imports and a ban on Chinese tourists from visiting the neighboring nation, as Seoul refused to give in Chinese pressure to scrap the decision.

While China's intimidation campaign is ramping up, the US as largely remained silent, Rogin said.

"The Chinese are trying to use this moment to rattle the nerves of an incoming administration in South Korea. If there's any time that we need to protect our ally, it's now," Sen. Cory Gardner (R-CO) was quoted as saying in the column. "THAAD is an incredibly important part of strengthening our alliance and showing our commitment to our alliance with South Korea."

Rep. Ted Yoho (R-FL) was also quoted as saying next week's summit is a perfect time for Trump to raise the issue.

"You've got to bring this stuff to the table," Yoho was quoted as saying. "Our goal is to protect our 28,000 troops in South Korea and protect the Korean people."

Rogin said that China's retaliatory measures contradict Xi's promise to pursue free trade and also his commitment to stand with the international community to do everything possible to counter the threat of North Korean missiles.

"Whether the Trump administration stands up for South Korea, especially during next week's summit with Xi, will send a clear signal to all Asian allies about whether or not the United States is as committed to their security as before," Rogin said. (Yonhap)