US Secretary of State Mike Pompeo on Tuesday asked Washington's think tanks to disclose foreign funding, warning of Chinese and Russian backing for the institutions known for wide influence on US policy.
Washington's think tanks have for decades served as homes in waiting for US experts when they are out of government and most aggressively seek funding -- although foreign money is most likely to come from nations friendly to the United States.
Pompeo called on think tanks that seek to cooperate with the State Department to disclose "prominently" on their websites any foreign funding, including by state-supported entities.
"Disclosure is not a requirement for engaging with such entities. Department staff will, however, be mindful of whether disclosure has been made and of specific funding sources that are disclosed when determining whether and how to engage," Pompeo said in a statement.
"We hope one day soon that US efforts to promote free and open dialogue about economic and personal liberty, equal citizenship, the rule of law and authentic civil society will be possible in places such as China and Russia."
President Donald Trump's administration has in recent months ramped up pressure on China, with Pompeo taking particular aim at its sources of influence in the United States.
In August, the State Department stepped up regulations for Confucius Institutes, which China has set up at US universities to offer language training but which critics say toes the communist state's official line.
Prominent US think tanks and universities have opened centers in China, stirring a debate on whether they are sacrificing US principles of free speech to engage in the rising power.
But the Center for International Development, a left-leaning think tank, in a study this year found that direct funding of Washington think tanks comes overwhelmingly from friendly nations.
Norway was the biggest funder, giving $27.7 million from 2014 through 2018 to the top 50 US think tanks, followed closely by Britain, according to the study.
Norway overwhelmingly gave its money to two think tanks focused on development and the environment.
Other key foreign sources of funding at Washington think tanks include oil-rich Gulf Arab monarchies as well as Taiwan, which has cultivated relations across Washington as it relies on US support in the face of pressure from Beijing.