The US is finally giving Ukraine's military cluster munitions, deadly and controversial explosives that could be 'devastating' for Russia

• The US announced a new weapons package that includes cluster munitions for Ukraine on Friday.
• Cluster munitions are deadly and controversial, but they could boost Ukraine's counteroffensive.

Ukraine has pressed the US for months to provide cluster munitions, highly lethal — and controversial — weapons, and now, after nearly 500 days of war, the US has finally agreed to send them.

The White House and Pentagon announced a new $800 million security assistance package for Ukraine on Friday that, for the first time, includes cluster munitions. Experts say these bombs will be useful to Kyiv's military in its grueling and bloody counteroffensive as its forces push against a sprawling network of Russian defenses.

"It's a significant additional capability that they don't currently have," Kurt Volker, the former US special representative for Ukraine negotiations and American ambassador to NATO, told Insider. "There's no single thing that's ever just a game-changer, but every little bit helps."

More than 16 months into Russia's full-scale invasion, Ukraine has a wide range of Western weapons at its disposal. These include UK-provided Storm Shadow cruise missiles — hailed by officials for their battlefield success — and German-made Leopard 2 tanks, which have given Ukrainian forces greater firepower and mobility on the ground.

Movement on F-16 fighter jets and Army Tactical Missile Systems (ATACMS) could eventually prove promising as well. But as Ukraine enters the second month of its counteroffensive and continues to make small territorial gains in the occupied eastern and southern regions, cluster munitions could be heavy hitters at a time when Ukraine needs all the combat power it can muster, experts say.

Cluster munitions can be dropped from the air or fired as artillery and deal damage over a larger area. Ukraine's forces would be able to rain destruction down on Russians, eliminating more threats while consuming less ammunition. These munitions could be an advantage in the ongoing artillery fight in which Ukraine has at times found itself outgunned and a useful tool for clearing fortifications.

Though contentious, Friday's announcement is not necessarily a surprising move, said Federico Borsari, a fellow with the transatlantic defense and security program at the Center for European Policy Analysis. The US and Ukraine have long-discussed the possibility of using these munitions. But it's also not an easy decision "considering several ethical and political implications for these decisions," he said.

The weapons first saw major use in World War II as German-made "butterfly bombs" hit the battlefield and became standard munitions in the later part of the 20th century.

Modern cluster bombs are canisters that carry dozens of little bomblets inside and can be ground-launched as missiles or artillery or dropped from aircraft. In this case, the US is sending Ukraine 155 millimeter artillery shells called dual-purpose improved conventional munitions (DPICMs), which break apart and scatter smaller explosives over a large area. Because these submunitions cover lots of ground, it allows them to threaten several enemy positions at once, which can quickly overwhelm and wreak havoc.

The munitions could be especially "devastating against Russians in trenches that don't have overhead cover," said Ben Hodges, a retired lieutenant general who headed US Army Europe. "And they'll be devastating against any Russian artillery that is spotted and within range."

Some cluster bomb canisters, like the air-launched Mk 20 Rockeye, also known as the CBU-100, can contain hundreds of bomblets and "will spread across a territory based on the altitude," Borsari said. "And this type of capability is very useful especially against armored vehicles and tanks." And any munition fired by a 155 millimeter Howitzer cannon, like the M864, will be useful for hitting armor or personnel targets, he added.

But cluster bombs won't be a silver bullet for Ukraine's counteroffensive against fortified Russian defenses. Ukraine will need to use them carefully in order to avoid adding more unexploded bombs to Russian minefields, and any area riddled with cluster bombs is basically a dead man's zone for both Kyiv and Moscow's forces, Borsari added.

Indiscriminate risk to civilians

Ukraine has long been asking the US for cluster bombs, but there hasn't been much movement on the weapons until now due in part to widespread concerns about a higher-than-acceptable dud rate, which is to say that they sometimes fail to explode on impact and wind up posing a tremendous risk to civilians for years to come.

In 2008, 108 nations signed the Convention on Cluster Munitions to prevent the use, transfer, or development of cluster bombs, citing the capacity for indiscriminate destruction spread over an area and how unexploded bombs threaten civilians. This came after the 2006 Lebanon War, during which Israeli forces were accused of firing millions of cluster bombs into the country.

The bombs are currently banned in over 120 countries, including many NATO allies, because of concerns over potential civilian causalities. The US, Ukraine, and Russia, however, are not parties to agreements banning their use.

Due to their range and movement, cluster munitions can be unpredictable and hit outside their intended target. The bomblets that don't explode can remain active for years and effectively become landmines, posing major risks to civilian activities even after the fighting has ceased.

Advocacy groups such as Amnesty International have said that they deeply oppose the use of cluster munitions in Ukraine, calling them "an indiscriminate weapon that presents a grave threat to civilian lives, even long after a conflict has ended."

"Their transfer and use by any country under any circumstances is incompatible with international law. The Biden Administration must understand that any decision enabling the broader use of cluster bombs in this war will likely lead to one predictable outcome: the further death of civilians," the watchdog organization said in a statement on Thursday.

Human Rights Watch has previously accused both Russia and Ukraine of using cluster munitions in the war, with Russian use greatly exceeding usage by the Ukrainians. The organization observed Russia using the explosives to attack civilian areas like schools and hospitals and that Ukraine using the weapons in Russian-controlled areas in and around the eastern city of Izium last year.

During a White House briefing on Friday, National Security Advisor Jake Sullivan told reporters that Ukraine has delivered written assurances that it will minimize use of the US-provided cluster bombs in areas where civilians could be located nearby. With the situation on the battlefield still very much fluid, Sullivan said it's an "ongoing" conversation about where the bombs can be deployed.

"The idea that Ukrainian men and women fighting for the armed forces of Ukraine want to willy nilly use these things in a way that are going to harm Ukrainian citizens, which is somewhat implied in the questions, I find at odds with their fundamental desire to protect their countrymen and their willingness to put their lives on the line to protect their countrymen," he added.

In announcing the new security package, Colin Kahl, the undersecretary of defense for policy, said on Friday that the dud rate for the American DPICMs is lower than that of Russia's munitions, specifically less than 2.35% compared to Russia's 30-40%.

"I'm as concerned about the humanitarian circumstance as anybody. But the worst thing for civilians in Ukraine is for Russia to win the war," Kahl said. "And so it's important that they don't."