According to US officials, Russia has asked China for military equipment to support its invasion of Ukraine.

US officials told the Financial Times that Russia had requested military equipment since the start of the invasion. They wouldn't say what Russia had requested.

A person familiar with the situation said the US was preparing to warn allies about the situation and that China may be preparing to help Russia. There were signs that Russia was running out of weaponry as the war in Ukraine entered its third week, according to other US officials.

The White House didn't say anything. The Chinese embassy in Washington did not respond to a request for a comment.

Jake Sullivan, US national security adviser, heads to Rome on Monday for talks with China's top foreign policy official. Sullivan would warn China that it would have consequences if it helped Russia prosecute the invasion, according to people familiar with the situation.

Sullivan warned China not to help Russia circumvent the sanctions imposed on it by the US and its allies.

Sullivan told NBC television that neither China, nor anyone else, can compensate Russia for its losses.

The request for equipment and other kinds of military assistance comes as the Russian military struggles to make as much progress in Ukraine as western intelligence expected.

The China-Russia relationship has grown stronger as both countries express their opposition to the US over everything from Nato to sanctions.

China has not condemned Russia for invading the country but has portrayed itself as a neutral actor. The US has not seen any sign that the Chinese are willing to put pressure on Putin.

The Beijing-Moscow partnership was described in a joint statement signed by the two leaders as having "no limits", in another sign that the two capitals were drawing closer together.

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