UNITED NATIONS >> China warned today that its critical relationship with the United States could break “like a glass,” and used the most global of stages to warn the Trump administration it wouldn’t be pushed around on trade.

Foreign Minister Wang Yi insisted that his country “will not be blackmailed” or bow to pressure. “Protectionism will only hurt oneself, and unilateral moves will bring damage to all,” he told the U.N. General Assembly gathering of world leaders.

President Donald Trump this week cranked up punitive tariffs on China, and Beijing responded in kind, escalating a trade war between the world’s two largest economies. Trump upped the ante by then accusing China of meddling in the upcoming U.S. midterm elections because it opposes his trade policies. He has presented little evidence to back up the allegations, which China says are untrue.

Wang, in separate remarks at a think tank, said U.S.-China relationship was at a critical point, four decades since ties were normalized.

“The relationship between our two countries is a common asset. It must be preserved and valued. It’s the result of generations of people’s efforts,” Wang said. “It’s like a glass. It’s easy to break it” and would be difficult to repair, he said.

Although Wang presented China as upholding multilateral institutions — drawing an implicit contrast with Trump’s anti-globalist stance — Beijing’s top diplomat said the suspicions that China seeks global hegemony and to displace the U.S. as a world leader is false. But he warned it’s an idea that is spreading, amplifying differences between the two countries.

“This is a serious strategic misjudgment,” Wang told the Council on Foreign Relations in New York, “that will be extremely detrimental to U.S. interests and the future of the United States.”

He said China rather seeks a path of peaceful development. He defended China’s assertive behavior in the South China Sea, where it has built man-made islands to reinforce its sweeping territorial claims that are disputed by its neighbors. He said military facilities on those islands are for defensive purposes to counter military activities by other nations in the area, including the United States.

Wang also defended China’s recent participation in military drills with Russia that have added to U.S. anxiety that its key strategic rivals are setting aside historical differences and teaming up against it. He said military-to-military ties are normal to build “mutual understanding.”

On human rights, Wang was asked about the reported harsh treatment of Uighur Muslims in China’s far west. He maintained that China had brought law and order to a region once blighted by terrorism. The Trump administration is reportedly considering sanctions in response to members of the religious minority being forced into “re-education” camps on a massive scale.

Notwithstanding all these differences, the main driver of the current discord between the U.S. and China is trade.

Trump increased tariffs Monday on $200 billion of Chinese goods. Beijing responded by imposing penalties on $60 billion of American products. That was on top of an earlier duty increase by both sides on $50 billion of each other’s goods. The tit-for-tat is fueling anxiety that smaller nations will suffer.

“There is a trade war going on between the two most powerful nations, and the rest of the world is feeling the pain,” Malaysian Prime Minister Mahathir Mohamad told the General Assembly on today.

Behind the trade dispute are U.S. allegations that China uses predatory tactics to overtake American technological dominance. These tactics, the U.S. charges, include cyber-theft of U.S. companies’ trade secrets and a requirement that foreign companies hand over proprietary technology as the price of access to the Chinese market.

Wang denied that China was stealing technology and forcing companies to transfer technology as a condition for investing in the country. He described instead a symbiotic commercial relationship in which the U.S. companies have a comparative advantage in technology and work in partnership with Chinese firms to help them access China’s growing market.

He said China has benefitted from opening up its economy and would continue to welcome foreign investment. “We hope American companies will continue to have confidence in the Chinese market,” Wang said.