Washington: US national security advisor Jake Sullivan on Sunday said there would be "real costs" for China if it provides military aid to Russia in its war on Ukraine, CNN reported.

"From our perspective, actually, this war presents real complications for Beijing. And Beijing will have to make its own decisions about how it proceeds, whether it provides military assistance. But, if it goes down that road, it will come at real costs to China. And I think China's leaders are weighing that as they make their decisions," Sullivan told CNN.

Sullivan said that the US is "not just making direct threats. We're just laying out both the stakes and the consequences, how things would unfold. And we are doing that clearly and specifically behind closed doors."

According to CNN, Sullivan's comments come at a critical point in the Ukraine war. The US has intelligence that the Chinese government is considering providing Russia with drones and ammunition for use in the war, three sources familiar with the intelligence told CNN.

According to sources, it appears that Beijing has not made a decision yet, as negotiations between Russia and China about the price and scope of the equipment are ongoing.

"I can level with the American people in saying that war is unpredictable," Sullivan said on Sunday when asked by CNN if the US could continue supporting Ukraine at current levels a year from now. "One year ago, we were all bracing for the fall of Kyiv in a matter of days. One year later, Joe Biden was standing with President Zelensky in Kyiv declaring that Kyiv stands."

"So, I cannot predict the future, and nor can anyone else. And anyone who is suggesting they can define for you how and when this war will end is not levelling with the American people or anyone else," he said, according to CNN.

Spokesperson for the US Department of State, Ned Price on Sunday said that the US does not and never will recognize Russia's annexation of Crimea and that the peninsula is part of Ukraine.

"The United States does not and never will recognize Russia's purported annexation of the peninsula. Crimea is Ukraine," Price said in a press statement on Sunday.

"Nine years ago, Russia invaded Ukraine and seized Crimea, a clear violation of international law and of Ukraine's sovereignty and territorial integrity. The United States welcomes the efforts of Ukraine's Crimea Platform to focus global attention on Russia's continued occupation," Price said, according to the US Department of State.