White House National Security Advisor Jake Sullivan confirmed on Friday that although the decision was "difficult to make", US leader Joe Biden ultimately decided to provide Ukraine with cluster munitions for its counteroffensive after consulting with allies and lawmakers.

During a press briefing, Sullivan said: "It's a difficult decision...There was a unanimous recommendation from the national security team, and President Biden ultimately decided, in consultation with allies and partners and in consultation with members of Congress, to move forward on this step".

Just hours before, humanitarian organizations condemned the initial plans to supply the cluster munitions after citing the long-lasting threat posed by them since they leave behind unexploded bomblets.

Read more: Pentagon believes banned cluster munitions would be useful for Ukraine

Baptiste Chapuis of Handicap International - Humanity and Inclusion (HI) said: "This is a death sentence to civilians over the long term. There are people who have not yet been born who will fall victim" to cluster bombs.

This comes just before the NATO summit in the Lithuanian capital Vilnius next week. 

Amnesty International researcher Patrick Wilcken said in a statement, "The USA's plan to transfer cluster munitions to Ukraine is a retrograde step, which undermines the considerable advances made by the international community in its attempts to protect civilians from such dangers," adding that it "urges the USA to reconsider".

"There is also the question of physical access to affected areas for humanitarian organizations," HI's Chapuis told AFP. The bombs' use can "prevent a lifeline reaching affected populations," he continued.

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Russia already warned the US against sending the cluster munitions to Ukraine, and Russian Ambassador to the UN Vassily Nebenzia argued it would count as a bigger step toward escalating the conflict.

Late last month, the US military said that despite it being banned by most countries, supplying Ukraine with cluster bombs could be useful against Russia.