Pompeo is in Singapore for multilateral meetings amid tensions over North Korea, trade and tariffs.
Successive governments have made some efforts to make officials more accountable to the public, but analysts say more needs to be done.
Who Is Chinese Professor Sun?
Agreement aims to prevent violence in disputed waters.
International Organization for Migration reports thousands of Rohingya refugees are at risk of falling prey to human traffickers who exploit them sexually and for forced labor.
US secretary of state's trip comes amid doubts about Pyongyang's commitment to denuclearize.
Wenguang Sun, who is critical of China's human rights record, has not been heard from since the Wednesday evening show.
Trump administration seeking to ratchet up pressure for trade concessions by proposing a higher 25-percent tariff on $200 billion worth of Chinese imports.
The annual meeting of the 10-nation bloc opens with security concerns.
US official, who spoke on the condition of anonymity, said Pyongyang gave almost no information to help identify the remains.
Secretary of State Mike Pompeo is heading to Singapore for ASEAN meetings, focused on a free and open Indo-Pacific and regional security.
Yingluck Shinawatra fled the country last August to avoid being jailed over a rice subsidy scheme that ran up losses in the billions of dollars.