U.S. Defense Secretary Lloyd Austin visited Cambodia on Tuesday in an effort to reset ties with the staunch China ally.
Washington's relationship with the Southeast Asian nation has been deteriorating for years, with China pouring in billions of dollars in infrastructure investments under Cambodia's former leader Hun Sen.
The United States has voiced concerns over a key Cambodian naval base that is being upgraded by Beijing, which it says could be used to boost the Asian giant's influence in the Gulf of Thailand.