Susan Rice speaks about the Security Council's passage of a resolution expanding sanctions on North Korea, at the White House in Washington June 12, 2009. Reuters White House national security officials said Thursday there was no evidence to back Republican presidential hopeful Ben Carson's claim that China has gotten involved in the Syrian conflict.

Carson's comment, which confounded foreign-policy experts, came in response to a question at Tuesday's Republican presidential debate about President Barack Obama's decision to send 50 members of special-operations forces to Syria.

The retired neurosurgeon said that having US special-ops forces in Syria is better than not having them there, and then noted that Syria is a "very complex place."

"You know, the Chinese are there, as well as the Russians, and you have all kinds of factions there," Carson said.

At the White House press briefing on Thursday, National Security Adviser Susan Rice pushed back on that claim.

"I really can’t speak to what [Carson] was referring to, but unless you’re talking about having a diplomatic presence, I’m not sure what he was referring to," Rice said. "I have not seen any evidence of Chinese military involvement in Syria."

Deputy National Security Adviser Ben Rhodes pointed out that it wouldn't make much sense for China to get involved in the Syrian civil war, which has dragged on for more than four years as President Bashar al-Assad has struggled to maintain his authoritarian grip on power.

"China makes it a practice to not get extended into military conflicts in the Middle East," Rhodes said. "Their policy over years, if not decades, is to not be overextended in military exercises."

This echoes what foreign-policy experts have said about the likelihood of Chinese involvement in Syria.

"This is very far from China's fight," Ian Bremmer, president of the Eurasia Group and author of the book "Superpower," told Business Insider on Wednesday. "They don't want responsibility for it, there's no potential diplomatic or security win for Beijing."

Bremmer said that while there has been unsubstantiated speculation recently about China and Syria, the Chinese government "has made clear that they don't have any forces there and they aren't planning to send any."

During a press conference on Wednesday in Lynchburg, Virginia, Carson attempted to clarify his statement.

"China has been trying to extend its influence not only throughout the Middle East but throughout Africa and in several [other] locations," he said. "And their interests extend into that region as well. I would have to refer you to some other people to get you to the actual data. But they've shown it to me."

And Armstrong Williams, a top Carson adviser, also defended his remarks on Wednesday. He told Business Insider that Carson's information on Chinese involvement in Syria is unconfirmed, but that he had heard it from multiple intelligence sources.

"During Dr. Carson’s conversations with military operatives and people in Iraq, in that part of the world, [they] discussed with him multiple reports that Chinese military advisers are on the ground in Syria operating with Russia special-operations personnel," Williams told Business Insider.

Williams said that Carson had also heard reports about "new Russian and Chinese munitions, ammunition, and weapons" that are reportedly showing up in both Syria and Iraq.

"We have many intelligence groups that speak to Dr. Carson and this is something that’s very consistent in what they’ve been saying in the intelligence community," Williams said.