In an interview on CNN's "Fareed Zakaria GPS" that aired July 9, Biden justified the decision saying he discussed it both with allies and with congressional lawmakers.

"It took me a while to be convinced to do it," Biden said in the interview, explaining the Ukrainians needed to break through entrenched Russian lines. "This is a war relating to munitions, and they are running out of that ammunition and we're low on it."

Biden said the decision was temporary until the U.S. has more 155mm artillery shells to provide the Ukrainians for their counteroffensive.

"But the main thing is they either have the weapons to stop the Russians now ... or they don't," he said. "And I think they needed them."

Cluster munitions, also known as cluster bombs, are ground-launched or air-dropped explosives that contain smaller submunitions, which increase the blast radius and the potential casualties or damage to physical structures.

The Holy See has condemned the use of cluster munitions, which Russia has used in Ukraine, including in attacks on civilians. The Holy See has called for universal adherence to the Convention on Cluster Munitions, a 2008 treaty signed by over 100 nations, which the Holy See at the time declared was necessary for the sake of ??the "protection of civilians during and after conflicts from the indiscriminate effects of this inhumane type of weapons."

The United States has not ratified the treaty and is thus not legally bound by it. Federal law prohibits the production, use or transfer of cluster munitions with a failure rate exceeding 1%; however, Biden is bypassing those restrictions.

Neither Ukraine nor Russia are bound by the treaty.

Despite Ukraine's just cause to defend itself, one Catholic expert said, the church opposes cluster munitions themselves.

Mary Ellen O'Connell, a professor at Notre Dame Law School who specializes in international law and conflict resolution, told OSV News Ukraine "has the legal and moral right to defend itself."

"States engaged in armed conflict are permitted to intentionally target an adversary's armed forces, something law enforcement officials operating in peacetime have no right to do," O'Connell said. "This combatant's privilege allows the military to use weapons permissible only within armed conflict hostilities. However, there are limits on the means and methods in combat."

O'Connell said that separately from the legal or moral validity of the conflict itself, the weapons used in that conflict should be evaluated on factors including, "Can the weapon discriminate between civilians and fighters?" and "could the weapon inflict unnecessary suffering?"

"Cluster munitions cannot discriminate between civilians and fighters," O'Connell said. "Unexploded bomblets may kill civilians weeks, months or years after a battle. Asserting that Ukraine will lose and civilians will suffer if the U.S. does not provide these weapons is misleading at best. An unlawful weapon is never permissible to use because of military necessity."

O'Connell suggested an alternative, arguing, "The U.S. has artillery shells it can send -- the president just wishes to hold them in reserve; other states have artillery shells and can be persuaded to send them as well."

"More importantly, Russia's allies need to be persuaded to stop assisting it directly or indirectly," she said. "When Russia is isolated, President (Vladimir) Putin may finally listen to the peace proposals of Pope Francis and others."

O'Connell also sees risks to Ukraine's international standing.

"If Ukraine uses banned weapons, it will lose some of the support it has now," she said, "and Russia's allies will see little reason to support Kyiv over Moscow."

Biden's decision to provide Ukraine with these weapons as it seeks to fend off Russia's invasion prompted some criticism within Biden's own party, but praise from some Republicans who rarely align with Biden.

Sen. Tom Cotton, R-Ark., offered his support in a July 7 statement.

“For Ukrainian forces to defeat Putin’s invasion, Ukraine needs at least equal access to the weapons Russia already uses against them, like cluster munitions," Cotton said. "Providing this new capability is the right decision -- even if it took too long -- and is one I’ve long supported.”

However, Rep. Betty McCollum, D-Minn., ranking member of the House Appropriations Subcommittee on Defense, stated the move is an "unnecessary and a terrible mistake."

"Allowing legacy U.S. cluster munitions onto the battlefield in Ukraine undermines our moral authority and places the U.S. in a position that directly contradicts 23 of our NATO allies who have joined the Convention on Cluster Munitions," McCollum said in a July 7 statement. "The legacy of cluster bombs is misery, death, and expensive cleanup generations after their use."

McCollum noted how decades after the Vietnam War ended in 1975, the U.S. is paying "tens of millions of dollars annually to remove cluster munitions in Laos ... as these remnants of war continue to kill and maim civilians."

"As a strong supporter of the Biden administration’s policy in Ukraine, I must state in the strongest possible terms my absolute opposition to the U.S. transferring cluster munitions," she said. "These weapons should be eliminated from our stockpiles, not dumped in Ukraine."

Ukraine's government, however, has welcomed the provision of cluster munitions as its counter-offensive makes slow progress against entrenched Russian defensive lines on Ukraine's territory.

Ukrainian President Volodymyr Zelenskyy thanked Biden in a July 7 statement for a "timely, broad and much-needed defense aid package from the United States."

Zelenskyy said Ukraine is grateful to the American people and to Biden "for decisive steps that bring Ukraine closer to victory over the enemy, and democracy to victory over dictatorship."

"The expansion of Ukraine's defense capabilities will provide new tools for the de-occupation of our land and bringing peace closer," he said.