WASHINGTON (AP) — U.S. intelligence suggests China is considering providing arms and ammunition to Russia, an involvement in the Kremlin’s war effort that would be a “serious problem,” Secretary of State Antony Blinken said.

Blinken said the United States long has been concerned that China would provide weapons to Russia. He pointed to Chinese leader Xi Jinping’s promise to Russian President Vladimir Putin of a partnership with “no limits” when they met just weeks before Putin sent his troops into Ukraine on Feb. 24, 2022. Since then, ties between the two countries have only grown stronger.

“We’ve been watching this very, very closely. And, for the most part, China has been engaged in providing rhetorical, political, diplomatic support to Russia, but we have information that gives us concern that they are considering providing lethal support to Russia in the war against Ukraine,” Blinken said in an interview that aired Sunday, a day after his meeting at a security conference in Munich with Wang Yi, the Chinese Communist Party’s most senior foreign policy official.

“It was important for me to share very clearly with Wang Yi that this would be a serious problem,” Blinken said.

With Putin determined to show some progress on the battlefield as the war nears the one-year mark, Russian forces have been on the offensive in eastern Ukraine.

“The Ukrainians are holding very strong, the Russians are suffering horrific losses in this effort,” Blinken said. He estimated that Russia has 97 percent of its ground troops in Ukraine.

The Russians also are eager to capture more territory before Ukraine receives the more advanced weapons recently pledged by the U.S. and its European allies.

WATCH: Western nations accelerate air defense to Ukraine as Russia launches new offensive

“But what Secretary Blinken said is big news to me,” said Sen. Lindsey Graham, R-S.C. Graham said the world should “come down hard on China” if it provides lethal weapons to Russia and he advised Chinese leaders not to do anything rash.

“To the Chinese, if you jump on the Putin train now, you’re dumber than dirt,” he said. “It would be like buying a ticket on the Titanic after you saw the movie. Don’t do this.”

Graham said it would be the “most catastrophic thing that could happen to the U.S.-China relationship. … That would change everything forever.”

Tensions between Washington and Beijing have been heightened in recent weeks after the U.S. shot down what it says was a Chinese spy balloon. China insists it was used mainly for meteorological research and was blown off course.

READ MORE: China threatens to take measures against U.S. entities over downing of balloon

The U.S. ambassador to the United Nations, Linda Thomas-Greenfield, also expressed her concern about any effort by the Chinese to arm Russia, saying “that would be a red line.”

Retired Gen. Jack Keane, a former Army vice chief of staff, said he agreed with the Biden administration’s decision to expose China’s possible readiness to provide some lethal weapons to Russia. He said it may persuade China to hold off.

“And I think coming out and exposing and I would go further and tell them what we think they are attempting to provide, China will pull back likely after that public exposure,” Keane said.

Blinken and Graham were on ABC’s “This Week,” Thomas-Greenfield appeared on CNN’s “State of the Union” and Keane spoke on “Fox News Sunday.”

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