US Secretary of State Antony Blinken began a visit to Kazakhstan and Uzbekistan on Tuesday, as part of a drive to deepen US engagement with Central Asian nations against the backdrop of Russia's war in Ukraine.

Upon arrival in the Kazakh capital Astana, Washington's top diplomat said no country can ignore the threats posed by Russian aggression, not only to their territory but to the international rules-based order and the global economy.

"I reaffirmed the United States' unwavering support for Kazakhstan, like all nations, to freely determine its future," Blinken said after a meeting with the foreign ministers of the so-called C5+1 group, made up of the US and Kazakhstan, Kyrgyzstan, Tajikistan, Turkmenistan and Uzbekistan.

Kazakh Foreign Minister Mukhtar Tileuberd thanked his US counterpart for the commitment to his country's freedom.

But he signaled that Kazakhstan was unlikely to adopt either a pro-Russian or pro-Western position, but would continue to act in its own national interest given “the complex international situation”.

Tileuberdi said that while Kazakhstan has very close and historic ties with both Russia and Ukraine, it would not allow its territory to be used for any Russian aggression or sanctions evasion.

He also said that even though Kazakhstan shares the world’s longest land border with Russia, it did not see a threat from Moscow.

Blinken, who later flew on to the Uzbek capital Tashkent, said the US was "watching compliance with sanctions very closely". He added that Washington was giving companies time to detach themselves from Russian firms sanctioned by the West over Ukraine.

He announced $25 million in economic support, on top of $25 million already committed by the Biden administration to the region.

In Blinken's sights are all the former Soviet republics of Central Asia who fear that they will be future victims of Russian expansionism.

Although traditionally viewed as part of the Kremlin's sphere of influence, none publicly backed Moscow's full-scale invasion of Ukraine. Kazakhstan welcomed tens of thousands of Russians fleeing from the military call-up late last year.

However, all five Central Asian republics along with India -- which Blinken will visit next after Uzbekistan -- abstained in a vote to condemn the invasion as a violation of core international principles last week at the UN General Assembly on the first anniversary of the war.

For decades, Washington has tried to wean the ex-Soviet nations of the region from Moscow's influence, without great success. As members of the Commonwealth of Independent States, their ties to Russia remain deep economically, militarily and diplomatically.

Meanwhile, Alexander Lukashenko, the leader of Belarus and a close ally of Russia, was expected to arrive in Beijing on Tuesday for a state visit that will be watched for hints about China's attitude to Russia's war in Ukraine.

Despite Chinese claims of neutrality, US officials have warned that Beijing is considering sending military assistance to Russia. China denies this and last week put forward a 12-point peace plan for Ukraine.

China has long had a close relationship with Lukashenko, who has strongly backed Moscow, helped Vladimir Putin prepare for the invasion of Ukraine a year ago, and continues to host Russian troops, warplanes and other weapons.