US President Joe Biden said that the NATO has "never been more united than it is today" in the face of Russia's ongoing war against Ukraine.

Addressing the media after a NATO summit here on Thursday, Biden said that Russian President Vladimir Putin is "getting exactly the opposite of what he intended to have as a consequence of going into Ukraine".

The summit was held as the Russian invasion of Ukraine completed a month on Thursday after it was launched by Putin on February 24.

Biden said the US "has committed to provide over $2 billion in military equipment to Ukraine since I became President — anti-air systems, anti-armor systems, ammunition. And our weapons are flowing into Ukraine as I speak".

"And today, I'm announcing the US have prepared to commit more than $1 billion in humanitarian assistance to help get relief to millions of Ukrainians affected by the war in Ukraine."

The President said that his country will welcome 100,000 Ukrainians and also invest an additional $320 million to "bolster democratic resilience and defend human rights in Ukraine and neighbouring countries".

Biden also announced new sanctions on over 400 individuals and entities, including members of the Duma (Russian Parliament), Oligarchs, and Russian defence companies.

"In addition to the 100,000 US forces now stationed in Europe to defend NATO territory, NATO established, as you already know, four new battle groups in Romania, Hungary, Bulgaria, and Slovakia to reinforce the eastern front.

"Between now and the NATO summit in June, we will develop plans for additional forces and capabilities to strengthen NATO's defenses.

"We will adopt an updated Strategic Concept to ensure NATO is ready to meet any challenge in the new and more dangerous security environment," the American President added.