The US on Thursday urged China not to back Russia's war against Ukraine, saying the world must unite in opposition to Moscow's aggression.
“We don't think anybody should be on the sidelines,” National Security Council spokesman John Kirby told CNN.
“The whole world should be lined up against what [Russian President Vladimir Putin] is doing.
“This is not the time for any kind of business as usual with Mr Putin.”
Earlier, Chinese President Xi Jinping met Mr Putin on the sidelines of the Shanghai Co-operation Organisation summit in Uzbekistan.
It was the leaders' first in-person meeting since Russia invaded Ukraine in February.
Mr Putin thanked Mr Xi for his “balanced” approach to the Ukrainian crisis and blasted Washington’s “ugly” policies at a meeting that followed a major setback for Moscow on the battlefield.
He said he was ready to discuss China's unspecified “concerns” over Ukraine, saying he understood Mr Xi's concern after Russian forces suffered major losses in recent weeks.
The Chinese president did not mention Ukraine in his public remarks, nor was the war mentioned in Chinese government reports of the leaders' meeting.
Mr Kirby said it remained to be seen how much China would back Russia's war, noting that Beijing had not moved to materially support Mr Putin or to breach sanctions against Moscow.
The US is preparing to give Ukraine another $600 million in security assistance as Washington looks to boost Kyiv in its counter-offensive.
It would mark the 21st drawdown of US inventories since the war began. The previous drawdown of $675m was announced just a week ago.
Mr Kirby said the announcement was expected to come "very, very soon", although he declined to provide details.
Ukraine war latest — in pictures
Agencies contributed to this report
