President Donald Trump has criticized China for its “economic aggression” and has called for a large increase in investment restrictions. After failing to successfully negotiate for a reduction of the U.S.’s $375 billion trade deficit, the administration is enacting new tariffs on Chinese goods. These are expected to spark retaliation from the Asian market when they go into place July 6.

On the military front, the U.S. Defense Department has labeled China a “strategic competitor” and withdrew the country’s participation in a biennial international military exercise, scheduled to begin this week near Hawaii. The U.S. has also criticized China for its military buildup in the South China Sea—earlier this month, Mattis said China’s weapons expansion there was “for the purposes of intimidation and coercion,” adding that the U.S. would “compete vigorously” if needed.

Additionally, U.S. lawmakers have pushed for increased military support for the island of Taiwan, which China considers a province. This disagreement over who holds the power on this democratically run island is yet another point of contention between Beijing and Washington.

With diplomatic relations on the line, Mattis said he wants to simply “have a conversation.”

“I want to go in right now without basically poisoning the well at this point,” Mattis said earlier this week. “I want to go in and do a lot of listening.”

Mattis is also expected to address Chinese leaders about continuing efforts to denuclearize North Korea. China’s alliance with their volatile neighbor is longstanding; North Korean leader Kim Jong Un met with President Xi Jinping after his summit with Trump in Singapore earlier this month. While details are vague on how the White House aims to denuclearize North Korea, Mattis is expected to press for the cooperation of China’s leaders.

“The People’s Republic of China also want to denuclearize the Korean Peninsula. That’s their policy,” Mattis said.

Mattis is also scheduled to visit South Korea and Japan later this week.