Biden, Putin display their alliances with Ukraine war backdrop

US President Joe Biden and Russian President Vladimir Putin bolstered their respective alliances with Nato and China, days before the first anniversary of Moscow's invasion of Ukraine.

Global tensions between superpowers were highlighted on a day of diplomacy in Warsaw and Moscow on Wednesday. Biden promised that the United States "will defend literally every inch of Nato", the military alliance that includes some Eastern European countries bordering Russia.

Putin said Chinese leader Xi Jinping would visit Russia, saying relations had reached "new frontiers." Washington is concerned Beijing could provide material support for Moscow's war in Ukraine, which began on Feb 24 last year and has become the biggest land conflict in Europe since World War Two.

The war has displaced millions, left Ukrainian cities, towns and villages in ruins and disrupted the global economy.

Putin, in an address to mark Thursday's Defender of the Fatherland public holiday, said Russia will continue to pay increased attention to boosting its nuclear forces and will begin mass deliveries of Zirkon sea-launched hypersonic missiles. Russia is due to begin military exercises with China in South Africa on Friday and has sent a frigate equipped with hypersonic missiles.

Russia would also keep equipping its armed forces with advanced equipment and is boosting the production of conventional weapons, Putin said in the remarks issued by the Kremlin early on Thursday.

On Wednesday, Putin welcomed China's top diplomat, Wang Yi, to the Kremlin, and Wang also met separately with Foreign Minister Sergei Lavrov.

TASS news agency quoted Wang as saying China would "firmly adhere to an objective and impartial position and play a constructive role in the political settlement of the crisis".Lavrov and Wang had not discussed a reported Chinese peace plan, the Russian Foreign Ministry said.

The relationship between China and Russia, Wang said through an interpreter, was not directed against any third party, but in a clear jab at the United States, he said China and Russia would "not succumb to pressure from third parties."

Eastern flank of Nato

In Warsaw, Biden met with leaders of nine Eastern European countries that during the Cold War were either aligned with Moscow or part of the former Soviet Union. Some of them now are among the strongest supporters of military aid to Ukraine.

"As Nato's eastern flank, you are the front line of our collective defence. You know better than anyone what is at stake in this conflict. Not just for Ukraine, but for the freedom of democracies throughout Europe and around the world," Biden said.

The Kremlin says it regards Nato, which could soon expand to include Sweden and Finland, as an existential threat to Russia. On his trip this week, which included a visit to the Ukrainian capital Kyiv, Biden rejected Russia's contention that the West wants to control or destroy it.

Meanwhile, at a meeting on Wednesday of the 193-member United Nations General Assembly to mark the Ukraine war's anniversary, UN Secretary-General Antonio Guterres denounced Russia's invasion as a violation of the founding UN Charter and international law and called out Moscow's threats about possible use of nuclear weapons.

In two speeches last September Putin indicated that he would, if needed, use nuclear weapons to defend Russia.

"We have heard implicit threats to use nuclear weapons. The so-called tactical use of nuclear weapons is utterly unacceptable. It is high time to step back from the brink," Guterres said.

Putin suspended the New Start (Strategic Arms Reduction Treaty) on nuclear arms control with the United States on Tuesday, accusing Washington of turning the war into a global conflict by arming Ukraine.

Moscow would stick to agreed limits on nuclear missiles and keep informing the United States about changes in its deployments, a senior Russian Defence Ministry official said.

Biden said in an ABC News interview that he saw no change in Moscow's nuclear posture and did not think Putin's remarks meant Russia was thinking of using nuclear weapons.

Asked about Russia's suspension of participation in New Start, Biden called it "a big mistake" but said, "I don't read into that that he's thinking of using nuclear weapons or anything like that."

Battlefield

Russia, trying to secure full control of two eastern provinces forming Ukraine's Donbas industrial region, has launched repeated assaults. Russian troops managed to break through Ukrainian defences near the town of Kreminna on Tuesday but were pushed back and lost some of their heavy equipment, a senior Ukrainian official said on Wednesday.

Kreminna is about 70km north of Bakhmut, focus of the fiercest Russian attacks.

Russia controls around a fifth of Ukraine a year after starting what it called a "special military operation" to protect Russian security. Ukraine and its Western allies have described the invasion as an imperial-style land grab.

- Reuters