Spent cluster munitions in a field in Pereizne, in the Donetsk region of Ukraine on Aug. 27, 2022.
CNN  — 

The US will send cluster munitions to Ukraine as part of a new military aid package, national security adviser Jake Sullivan confirmed on Friday, following months of debate within the Biden administration about whether to provide Kyiv with the controversial weapons banned by over 100 countries, including key US allies.

“I’m not going to stand up here and say it is easy,” Sullivan told reporters. “It’s a difficult decision. It’s a decision we deferred. It’s a decision that required a real hard look at the potential harm to civilians. And when we put all of that together, 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 strategy.”

President Joe Biden approved the transfer of the munitions this week, officials told CNN. CNN first reported last week that the administration was strongly considering the move, as Ukrainians forces have struggled to make major gains in their counteroffensive against Russia.

Throughout the conflict, the US has, in the face of intense lobbying, gradually agreed to Kyiv’s requests for more aggressive weaponry, including Patriot Missile systems and modern tanks. But the decision to send cluster munitions marks a watershed moment with the Biden administration agreeing to send a weapon that most countries have agreed should have no place in modern warfare.

Biden said in an interview with CNN’s Fareed Zakaria on Friday that it was a “difficult decision” to provide Ukraine with cluster munitions for the first time but that he was ultimately convinced to send the controversial weapons because Kyiv needs ammunition in its counteroffensive against Russia.

“It was a very difficult decision on my part. And by the way, I discussed this with our allies, I discussed this with our friends up on the Hill,” Biden said, adding, “The Ukrainians are running out of ammunition.”

The munitions will be compatible with the US-provided 155 mm howitzers, a key piece of artillery that has allowed Ukraine to win back territory over the past year, according to the Pentagon. In a statement announcing a new round of aid to Ukraine, the Defense Department said the US will be providing “155mm artillery rounds, including DPICM,” or Dual Purpose Improved Conventional Munitions – the type of cluster munition the US currently has in its stockpiles.

Dr. Colin Kahl, the under secretary of defense for policy, told reporters on Friday that Ukraine gave “assurances in writing” that it would not use the cluster munitions in urban areas “that are populated by civilians, and that there would be a careful accounting of where they use these weapons.”

Risk to civilians

Cluster munitions scatter “bomblets” across large areas that can fail to explode on impact and can pose a long-term risk to anyone who encounters them, similar to landmines. Over 100 countries, including the UK, France and Germany, have outlawed the munitions under the Convention on Cluster Munitions, but the US and Ukraine are not signatories to the ban.

German defense minister Boris Pistorias said Friday that providing the munitions to Ukraine is “not an option” for Berlin because it is a signatory to the convention. But he declined to weigh in on the US decision to do so. “Those countries that have not signed the convention – China, Russia, Ukraine and the US – it is not up to me to comment on their actions.”

Human rights advocates have condemned the move. Human Rights Watch said in a report on Thursday that “transferring these weapons would inevitably cause long-term suffering for civilians and undermine the international opprobrium of their use.”

Biden will overrule statutory restrictions imposed by Congress on exporting munitions with a greater than 1% “dud” rate – the munitions the US is set to provide may have a dud rate of up to 2.35%, Pentagon press secretary Brig. Gen. Patrick Ryder said Thursday. Biden will invoke Section 614 of the Foreign Assistance Act to waive those restrictions, a defense official said, which allows the president to provide foreign aid regardless of export restrictions if it is in the national security interest of the United States.

The dud rate refers to how often the bomblets the munition scatters across a large area fail to explode, posing a long-term risk to civilians who may encounter them later. A higher dud rate means more of the scattered bomblets will fail to explode on impact. Ryder said the Russians have been using cluster munitions with a dud rate as high as 40%.

Kahl reiterated Friday that the Pentagon would not be providing munitions with a dud rate over 2.35%, a rate which was “demonstrated through five comprehensive tests conducted by the Department of Defense between 1998 and 2020.”

Ukrainian officials have been pushing the US to provide the munitions since last year, arguing that they would provide more ammunition for Western-provided artillery and rocket systems, and help narrow Russia’s numerical superiority in artillery.

Biden reluctant at first

Biden was reluctant at first, officials told CNN, given how many countries worldwide have banned the munitions.

But changing battlefield conditions inside Ukraine over the past three weeks prompted US officials to give them renewed and serious consideration, and the Pentagon recommended to Biden that the munitions be provided to Ukraine at least on a temporary basis until non-cluster ammunition is able to be resupplied, officials said.

It is not clear whether the heavy amount of artillery ammunition the Ukrainians have been expending day-to-day would be sustainable without the cluster munitions if the counteroffensive drags on, officials and military analysts said. Biden ultimately agreed with their assessment.

A defense official provided more information to CNN on Saturday about how the US military tested the cluster munitions that the Biden administration plans to send to Ukraine, to make sure that the munitions have a dud rate of 2.35% or lower.

The defense official said the testing of the munitions “was executed via live fire,” as opposed to a simulated or virtual test, and the most recent tests were conducted in 2020 at Yuma Proving Ground in Arizona by Joint Munitions Command employees.

“During the testing, a sample set from each lot in the test group is fired and the number of unexploded bomblets is assessed and recorded,” the official said. “That data is then compiled to develop the report, which includes dud rates.”

The official said that the types of cluster munitions the US is planning to send, the M864 and M483A1 models, were most recently tested in 2020 and 2017, respectively.

“We set aside 40 rounds from each of the 11 lots tested,” the defense official said. A “lot” is essentially a batch of ammunition, and the rounds were randomly selected by employees at the US Army’s Joint Munitions Command where the rounds are stored.

The official said the munitions were tested in multiple ways, including through “air burst” and “ground point detonation,” and from multiple distances, ranging from 15 to 30 kilometers.

“There are also multiple ways that the duds are counted to include photo tracking systems, acoustic systems and manual observation,” the official said.

Critics have raised questions about the military’s testing process, including whether it was done under ideal conditions or tested under different weather and terrain conditions that might affect how the munition reacts. The defense official did not address whether the munitions were tested under those different conditions.

Russia’s ambassador to Belarus, Boris Gryzlov, said the US decision was “a move of desperation.”

“As part of the continued assistance to the Kiev regime, Washington is considering the possibility of sending cluster munitions to Ukraine. There has been talk about it since spring,” Gryzlov told Russian state news agency TASS on Friday.

“Now, the ‘hawks’ in the West have realized that the much-advertised counter-offensive of the Ukrainian armed forces did not go according to plan, so they are trying at all costs to give at least some impetus to it. In fact, it is a move of desperation,” Gryzlov said.

CNN’s Jeremy Herb and Radina Gigova contributed reporting.