White House national security adviser Jake Sullivan underscored that there is no evidence that China has been providing military assistance to Russia in its war with Ukraine.

Responding to CIA Director William Burns's public assertion that he was confident in the intelligence that China was mulling the prospects of giving lethal aid to Russia, Sullivan stressed that doing so would be a "mistake" and that the United States will monitor the situation "carefully."

CIA DIRECTOR: US 'CONFIDENT' CHINA IS 'CONSIDERING' RUSSIA'S LETHAL AID REQUESTS

"We actually haven't seen them take a final decision to provide the aid to Russia, and we haven't seen the aid be provided to Russia. So we will watch carefully, we will be vigilant, and we will continue to send a strong message that we believe that sending military aid to Russia," Sullivan told CNN's State of the Union with Jake Tapper and Dana Bash.

Sullivan said that deciding to provide military aid to Russia "would be a bad mistake, and China should want no part of it."

China has publicly denied reports that it is weighing lethal aid, despite Burns' statement. When pressed about how the U.S. would respond, Sullivan demurred, opting to keep the U.S. communication with Beijing private, though he stressed that the consequences have been communicated with China.

Sullivan also took note of the "awkward" position that China finds itself in, given its relationship with Russia and eagerness to make inroads with countries irked by the invasion.

"China's position in this is much more awkward. In fact, there was just a vote at the U.N. General Assembly in which China abstained. They did not vote with Russia," Sullivan added. "They know that going all in with Russia in this war in Ukraine would alienate a substantial number of countries that they are working hard to maintain good relations with."

Both sides of the bloody war marked the one-year anniversary of the invasion last week on Feb. 24. President Joe Biden visited Ukraine and Poland to mark the anniversary. Meanwhile, Ukrainian President Volodymyr Zelensky reiterated his position that Ukraine will seek to retake Crimea, which experts fear could exacerbate the war.

Sullivan similarly demurred when asked about Zelenksy's remarks on Crimea, insisting he is not "going to get into hypothetical questions." He also echoed Biden's assertion that the U.S. has ruled out giving Ukraine F-16s fighter jets for now, despite Zelensky's pleas.

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He also spoke on the recent Wall Street Journal report that the Energy Department has concluded with "low confidence" that the lab leak theory was the most plausible origin explanation for the COVID-19 origin.

"President Biden specifically requested that the national labs, which are part of the Department of Energy, be brought into this assessment," Sullivan said. "And if we gain any further insight or information, we will share it with Congress, and we will share it with the American people. But right now, there is not a definitive answer that has emerged from the intelligence community on this question."