In a high-stakes phone call on Friday, President Joe Biden warned China's President Xi Jinping of "the implications and consequences" should China provide support to Russia in its invasion of Ukraine.

The White House, in statement released Friday afternoon, detailed President Biden's nearly two-hour virtual meeting with President Xi, which focused largely on Russia's invasion of Ukraine.

Biden "described the implications and consequences if China provides material support to Russia as it conducts brutal attacks against Ukrainian cities and civilians," while also underscoring his support for a diplomatic resolution to the conflict, according to the White House.

A senior Biden administration official described the conversation as direct, substantive and detailed.

According to the White House, Biden explained to Xi "the views of the United States and our Allies and partners" on the invasion, as well as their "efforts to prevent and then respond to the invasion," including the sanctions imposed on Russia.

Biden "described the implications and consequences if China provides material support to Russia as it conducts brutal attacks against Ukrainian cities and civilians" and "underscored his support for a diplomatic resolution to the crisis."

Biden did not lay out specific requests to China, the senior official added, but instead described in detail how the U.S. views the invasion, the international response and the possible implications if China or any other nation were to materially support Moscow.

“China will make its own decisions,” they added.

Biden and Xi also agreed on the "importance of maintaining open lines of communication, to manage the competition between our two countries," the White House said, with Biden detailing to Xi that the United States' "policy on Taiwan has not changed, and emphasized that the United States continues to oppose any unilateral changes to the status quo."

"The two leaders tasked their teams to follow up on today’s conversation in the critical period ahead," the readout concluded.

The U.S.-China relationship, long fraught, has only become more strained since the start of Biden’s presidency. Biden has repeatedly criticized China for military provocations against Taiwan, human rights abuses against ethnic minorities and efforts to squelch pro-democracy advocates in Hong Kong.

But the relationship may have reached a new low with the Russian invasion.

In the days after Putin deployed Russian forces in Ukraine, Xi’s government tried to distance itself from Russia’s offensive but avoided the criticism many other nations have leveled at Moscow. At other moments, Beijing’s actions have been provocative including amplifying unverified Russian claims that Ukraine ran chemical and biological weapons labs with U.S. support.

Earlier this week, the U.S. informed Asian and European allies that American intelligence had determined that China had signaled to Russia that it would be willing to provide both military support for the campaign in Ukraine and financial backing to help stave off the impact of severe sanctions imposed by the West.

Secretary of State Antony Blinken on Thursday reiterated that the Biden administration remains concerned that China is considering providing military equipment. He said Biden would make clear to Xi “that China will bear responsibility for any actions it takes to support Russia’s aggression, and we will not hesitate to impose costs.”

The White House says China has been sending mixed messages. There were initial signs that Chinese state-owned banks were pulling back from financing Russian activities, according to a senior Biden administration official.

But there have also been public comments by Chinese officials who expressed support for Russia being a strategic partner.

White House national security adviser Jake Sullivan and senior Chinese foreign policy adviser Yang Jiechi met in Rome this week for an intense, seven-hour talk about the Russian invasion and other issues.

Ahead of the Rome talks, Sullivan said the U.S. wouldn’t abide China or any other country helping Russia work around economy-jarring sanctions inflicted by the U.S. and other allies since the Feb. 24 invasion.

Sullivan also said the administration determined China knew that Putin “was planning something” before the invasion of Ukraine, but the Chinese government “may not have understood the full extent” of what Putin had in mind.

Xi and Putin met in early February, weeks before the invasion, with the Russian leader traveling to Beijing for the start of the Winter Olympics. The two leaders issued a 5,000-word statement declaring limitless “friendship.”

Beijing’s leaders would like to be supportive of Russia, but they also recognize how badly the Russian military action is going as an overmatched Ukrainian military has put up stiff resistance, according to a Western official familiar with current intelligence assessments.

The official said Beijing is weighing the potential “reputational blowback” of being associated with the Russian camp. The Chinese response to Russia’s request for help is still being formulated, the official said.

Though seen as siding with Russia, China has also reached out to Ukraine, with its ambassador to the country on Monday quoted as saying: “China is a friendly country for the Ukrainian people. As an ambassador, I can responsibly say that China will forever be a good force for Ukraine, both economically and politically.”

“We have seen how great the unity of the Ukrainian people is, and that means its strength,” Fan Xianrong was quoted by Ukraine’s state news service Ukrinform as telling regional authorities in the western city of Lviv, where the Chinese Embassy has relocated to.

Separately, in a reminder of China’s threat to assert its claim to Taiwan by force, the Chinese aircraft carrier Shandong sailed through the Taiwan Strait on Friday, just hours before the Biden-Xi call, Taiwan’s Defense Ministry said.

Any conflict over the self-governing island democracy stands to involve the U.S., which is legally obligated to ensure Taiwan can defend itself and treats threats to the island as matters of “grave concern.”

Chinese foreign ministry spokesman Zhao Lijian said he had no details about the ship’s passage through the strait, but added that “I believe the carrier has its routine training schedule, and it should not be linked with the communication between Chinese and American leaders.”

State media quoted Xi as saying China-U.S. relations had yet to “emerge from the dilemma created by the previous U.S. administration, but instead encountered more and more challenges,” singling out Taiwan as one area in particular.

“If the Taiwan issue is not handled properly, it will have an undermining impact on the relationship between the two countries,” Xi reportedly told Biden.