Chinese President Xi Jinping flew into Moscow on Monday where he was expected to press Beijing's role as a potential peacemaker in the Ukraine conflict while Russian President Vladimir Putin hoped for support against Western pressure.
Xi will be the first national leader to shake Putin's hand since the International Criminal Court (ICC) issued an arrest warrant for him on Friday over the deportation of Ukrainian children to Russia since its invasion.
Moscow said the charge was among a number of "clearly hostile displays" and Beijing said it reflects double standards.
Russia is presenting Xi's trip, his first since securing an unprecedented third term this month, as evidence that it has a powerful friend prepared to stand with it against a hostile West that it accuses of trying to isolate and defeat Moscow.
"We can feel the geopolitical landscape in the outside world undergoing drastic changes," Putin said in an article in China's People's Daily published on the Kremlin website, adding that he had high hopes for the visit from his "good old friend".
For Xi, the visit is a diplomatic tightrope.
China has released a 12-point proposal to solve the Ukraine crisis, but at the same time strengthened ties with Moscow.
China has repeatedly dismissed Western accusations that it is planning to arm Russia but says it wants a closer energy partnership after boosting imports of Russian coal, gas and oil following Putin's all-out invasion of Ukraine. Western sanctions on Russian energy mean Beijing has saved billions of dollars.
Xi arrived in Moscow on Monday afternoon and was due to hold "informal" talks with Putin, followed by dinner.
Formal talks are scheduled for Tuesday.
Xi wrote in an article published in Russia that the two countries adhered to the concept of "eternal friendship and mutually beneficial cooperation" and that China's Ukraine peace proposal, released last month, reflects global views.
"Complex problems do not have simple solutions," Xi wrote in Rossiiskaya Gazeta, a daily published by the Russian government, according to a Reuters translation from Russian.
Ukraine and its Western backers say any ceasefire would merely buy Putin time to reinforce ahead of a planned Ukrainian counter-offensive.
Ukrainian President Volodymyr Zelenskiy has said he will only consider peace settlements after Russian troops leave Ukrainian territory.
China's proposal contains no concrete proposal on how to end the year-long war which has killed tens of thousands of people, destroyed cities and forced millions to flee.
Putin welcomed China's offer to mediate and the Kremlin said he would provide Xi with detailed "clarifications" of Russia's position, without elaborating. Putin signed a "no limits" partnership with Xi last year shortly before he sent tens of thousands of troops into Ukraine to end what he said was a threat to Russia from its moves towards the West.
The US notes that China has declined to condemn Russia and given it an economic lifeline.
Alongside growing oil and coal deliveries to China, Putin said Russia was helping to build nuclear power reactors there and the two countries were deepening cooperation in space exploration and new technologies.
'THROW IT AWAY'
As Western pressure on Russia grows, Putin's administration has told officials to stop using iPhones because of concerns the devices are vulnerable to Western intelligence agencies, a newspaper reported on Monday.
"Either throw it away or give it to the children," the Kommersant daily quoted a participant of the meeting as saying.
Justice ministers from around the world will meet in London on Monday to discuss support for the ICC and several European Union countries are expected to sign an agreement in Brussels to buy 155 mm artillery shells for Ukraine.
Ukraine has identified the shells' supply as critical, with both sides firing thousands of rounds every day. The first joint orders are not expected until the end of May but EU officials hope the plan will encourage member states to send more of their stockpiles to Ukraine.
In Ukraine, fierce fighting continued in the eastern town of Bakhmut with each side launching counter-offensives. Ukrainian forces have held out in Bakhmut since last summer in the longest and bloodiest battle of the war.
Giving its regular morning roundup from the front, Ukraine's military said defenders in Bakhmut, Lyman, Ivanivske, Bohdanivka and Hryhorivka - all towns in the Donetsk region - had repelled 69 Russian attacks in the past day.
"Bakhmut remains the epicentre of hostilities," it said.
British intelligence said Ukrainian supply lines both west of Bakhmut and west of the town of Avdiivka, further south, were under pressure.
Ukraine's military said that Russian forces were on the defensive in the Kherson and Zaporizhzhia regions to the south.
Russia's Wagner mercenary group which is spearheading the assault on Bakhmut and has suffered heavy losses, plans to recruit some 30,000 new fighters by the middle of May, its founder Yevgeny Prigozhin said at the weekend.
In January, the United States assessed that Wagner had about 50,000 fighters in Ukraine, including 40,000 convicts Prigozhin had recruited from Russian prisons with a promise of a pardon if they survived six months.
Ukrainian officials have said that some 30,000 of Wagner's fighters have deserted or been killed or wounded, a figure that could not be independently verified.