Polish President Andrzej Duda said during his talks with US President Joe Biden, he asked about the possibility of speeding up military purchases (Getty Images)

US President Joe Biden said his Russian counterpart, Vladimir Putin, "cannot remain in power," calling the conflict in Ukraine Moscow's "strategic failure" in a speech given in Warsaw, Poland.

He compared Ukraine's fight against Russian troops to the "battle for freedom" which was waged against the Soviet Union in the 20th century. Biden said the world must prepare for a "long fight ahead.

Biden meets Ukrainian FM, Defense Minister in Warsaw

US President Joe Biden met with Ukrainian officials in the Polish capital, Warsaw, on Saturday, accompanied by his Secretary of State, Antony Blinken, and his Defense Secretary, Lloyd Austin.

The meeting took place with the Ukrainian counterpart of the delegation that accompanied Biden, Dmytro Kuleba, and Oleksii Reznikov, respectively, at the Marriott Hotel to discuss certain issues related to the war in Ukraine.

Ukraine has been pressuring its western ally and NATO to intervene against Russia and pump more weapons and assistance to Kiev, and these calls have even included calls from President Zelensky for the West to impose a no-fly zone over his country, which Brussels and Washington dismissed several times, citing the fact that this could lead to a war with Moscow.

"We are meeting our US counterpart [Blinken and Austin] in Warsaw together with [Reznikov]. This special 2+2 format allows us to seek practical decisions in both political and defense spheres in order to fortify Ukraine’s ability to fight back Russian aggression," Kiev's Kuleba said on Twitter.

This is the first meeting between US and Ukrainian officials since the start of the crisis, as the last meeting was between Biden and Kuleba in Washington just two days before the start of the Russian military operation in Ukraine.

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Biden meets Ukrainian FM, Defense Minister in Warsaw