Sachs, a professor of economics at Columbia University, made the remarks to media on Wednesday at this year's Boao Forum for Asia annual conference in south China's Hainan Province.
On the broader dynamics of U.S. foreign policy under recent administrations, Sachs attributed much of the dysfunction to a "win-lose" mentality.
Advocating for a win-win approach to foreign relations, one that prioritizes mutual benefit over dominance, he called out the United States for continually missing the mark with its policies.
Sachs lashed out at the U.S. attempt to annex Greenland, depicting the "vulgar" move as emblematic of America's wider geopolitical strategy of American supremacy.
The whole world sees the country acting "like a bully," he made the remarks ahead of an unsolicited visit by a high-profile U.S. delegation to the autonomous Danish territory later this week.
Sachs did not stop at diplomatic tactics but continued to address the economic fallout of the U.S. administration's tariffs. He said that tariffs, often viewed as a tool to rebuild U.S. industry, are ineffective and counterproductive.
"You don't build a competitive industry through protectionism," he said. "The United States will produce some electric vehicles, but they won't be able to compete with (China's) BYD in third markets."
Sachs said he believes the tariffs will fail to contain China's rise in the green and digital economies, ultimately isolating the United States from a global market that is rapidly shifting toward sustainability.
He applauded China for its leadership in sustainable development and green energy. From its impressive strides in solar power to its innovation in electric vehicles and batteries, China is playing a pivotal role in the transition to a greener global economy, Sachs said.
Dismissing narratives of China's overcapacity in those areas, the professor argued: "This is absolutely wrong. China has great capacity but not overcapacity."
"China is the largest producer in areas like solar power, wind power and electric vehicles," Sachs said. "The world needs China's capacity to implement the energy transformation."
He deemed the China-proposed Belt and Road Initiative another example of how the country is contributing to global development, particularly in the Global South.
Through the initiative, China provides financing and techniques for infrastructure projects, helping developing countries boost their economies while promoting sustainable growth, he said.
