A bomb is released from a Russian Su-34 strike fighter in Syria. (Russian Defense Ministry Press Service via AP)

After a breakdown of the recent cease-fire in Syria, Russian and Syrian air forces have resumed a bombing campaign that has extensively used cluster munitions, killing and maiming dozens of civilians, a leading human rights group said in a report released Thursday.

The report by the New York-based Human Rights Watch documented 47 different cluster munition attacks across three Syrian governorates since May 27. The majority of the attacks focused on Aleppo, where Syrian government forces backed by Russian air support and artillery have fought doggedly to dislodge opposition fighters located in the city.

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Cluster munitions are banned by 119 countries, but Russia and Syria are not party to the convention that prohibits their possession and use. Frequently airdropped but capable of being fired from artillery, cluster munitions are weapons often used to deny enemy forces important terrain by saturating an area in small tennis-ball-size bomblets, known as submunitions, which can explode on impact. But many of these small bombs do not explode, creating fields of highly unstable ordnance that maim and kill anyone, often civilians, who come across them.

Human Rights Watch has documented the use of 13 different types of cluster munitions in Syria.

“Since Russia and Syria have renewed their joint air operations, we have seen a relentless use of cluster munitions,” said Ole Solvang, deputy emergencies director at Human Rights Watch in the report. “The Russian government should immediately ensure that neither its forces nor Syria’s use this inherently indiscriminate weapon.”

Syrian government forces were first documented using cluster munitions in 2012 and following the start of Russia’s air campaign in late September, open source image analysts have highlighted pictures and footage showing Russian bombers loaded with the controversial weapons.

From Sept. 30 to Feb 27, Human Rights Watch recorded 34 cluster munition attacks across Syria. According to the report, the number of attacks dropped off from February to April, roughly during the same time that a nationwide cessation of hostilities went into effect. In May, opposition groups mostly entrenched around Aleppo, went on the offensive, and the number of cluster munition attacks spiked once more. According to the report, Human Rights Watch has received reports of upward of 150 cluster-bomb attacks since May but has not been able to verify many of them because of heavy fighting and poor communications.

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Syrian government forces, despite using a limited amount of cluster munitions, have primarily relied on crudely built barrel bombs as their go-to airdropped weapon. Packed with explosives and homemade shrapnel, the weapons have been used to devastating effect over Syria’s cities and countryside to kill and maim thousands of civilians and opposition fighters.

According to the Human Rights Watch report, the Russian-Syrian air campaign has used cluster munitions in two high-profile attacks in the past two months: one on a series of fuel trucks earlier this month and the other on U.S.-backed Syrian fighters in June. Aside from carrying cluster munitions, Russian aircraft have also been recently spotted loaded with incendiary bombs. Social media posts have appeared to confirm an uptick in their use as well, though it is unclear whether they are being dropped by Russian or Syrian aircraft.

In an interview last month, Mary Wareham, the arms advocacy director at Human Rights Watch, said that her group has begun an in-depth look into the reports to see whether incendiary weapons have been dropped on civilian populations. Russia is party to a U.N. protocol that bans the use of airdropped incendiary bombs on areas that contain large numbers of civilians, but Syria is not.

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Despite the documented presence of problematic munitions strapped to the underbelly of their aircraft, the Russian Defense Ministry released a statement in December noting that the Russian air force does not use cluster munitions and does not store them at its main air base in Syria. While the United States has also not banned the use of cluster munitions, an Air Force spokesman said that U.S. forces and other coalition aircraft flying over Iraq and Syria have not used them during their bombing campaign against the Islamic State.

“U.S. aircraft have only employed precision guided or direct fire weapons in Operation Inherent Resolve,” Lt. Col Chris Kairns said in an email. “Fighting against an enemy that wraps itself around the population requires painstakingly careful targeting, discipline, and pinpoint accuracy and precision.”

Although the United States has not used the munitions in its anti-Islamic State campaign, it has continuously supplied cluster munitions to its regional allies, including Saudi Arabia, which has used them in its recent bombing campaign over Yemen.

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