American-made precision-guided bombs, which are aimed at specific targets and ideally minimize civilian casualties, were used in airstrikes on Gaza that killed dozens of Palestinians, including women and children.
The weapon, a GBU-39 (small caliber bomb), was used in Thursday's attack on a former United Nations school and in Rafah on May 26. The Israeli military defended its actions in both cases, saying the attacks were aimed at militants who were using civilians as human shields. Gaza health officials said civilians were also killed, and there were videos and photos of women and children among the dead.
Two weapons experts told The New York Times that Israel appears to have increased its use of bombs this year. Early in the war, just 10 percent of its air strikes on Gaza used bombs. As the latest wave of Israeli attacks has shown, even relatively small bombs can cause serious civilian casualties.
“The problem is that using small arms or precision-guided weapons doesn't mean that civilians won't be killed, or that all attacks suddenly become legal,” said Brian Kassner, an arms expert at Amnesty International.
Early in the war, Israeli forces launched a full-scale invasion of Gaza cities with tanks, artillery and 2,000-pound bombs, drawing international condemnation for causing large numbers of civilian casualties.
Under pressure from the Biden administration, Israel has shifted its warfighting strategy to low-intensity operations and targeted raids and is now relying more on the GBU-39, a 250-pound bomb containing 37 pounds of explosives that is fired from a fighter jet, analysts said.
Ryan Brobst, a military analyst at the Foundation for Defense of Democracies, said the change appears to have begun in January or February and “likely explains the change in weapons being used.”
An unexploded GBU-39 was found last month at a school in Jabalia, in the northern Gaza Strip, and the distinctive tail of the same type of bomb was found at the site of a May 13 attack on homes and a school in Nuseirat, further south, killing around 30 people.
Analysts also said GBU-39 wreckage was found outside a home destroyed by Israeli airstrikes in Rafah in April, at an unspecified location in Gaza in March, and in Tal al-Sultan in January.
Israel's use of the GBU-39 represents just a fraction of the tens of thousands of airstrikes it has carried out with a range of weapons overall, experts estimate, but remnants of the bombs after the attacks and Israel's requests to replenish its stockpiles indicate a clear Israeli increase in its use of the weapon, analysts said.
“We've seen a significant increase in GBU-39 wrecks in recent months,” Kastner said, “and the trend is going from larger to smaller.” (But Amnesty researchers continue to see evidence of larger munitions, such as the Mark 80 series, which can weigh up to 2,000 pounds, that were fired into populated areas early in the war, he said.)
Israel says the Israeli army is the only one that has an accurate list of how often and where it has used GBU-39s since the war began in October after Hamas militants killed 1,200 Israelis and took 250 hostage. Israeli military officials did not answer questions about the weapon in Gaza but said in a written statement to The New York Times on Thursday that “whenever the type of target and operational circumstances permit, the IDF prefers to use lighter munitions.”
The statement added that “the munitions selected by the IDF are chosen in a manner that takes into account the environment and matches the munition type to the specific target with the intention of achieving military objectives while minimizing harm to civilians as much as possible.”
During the first six weeks of the war, Israel periodically dropped 2,000-pound bombs on southern Gaza, where residents were told to flee for their safety. A December investigation by The Times concluded that the bombs caused apartment buildings to collapse into huge holes, killing thousands.
In November, U.S. officials urged Israel to use smaller bombs to better protect civilians, just a month before Boeing, the manufacturer of the GBU-39, sped up delivery of 1,000 of the weapons out of a 2021 order that had yet to be completed.
By December, President Biden was warning Israel that it was losing global support for its war because of “indiscriminate bombing.”
“We've made it very clear to Israel that the safety of innocent Palestinians remains a major concern, and they know that,” Biden said on Tuesday. “So any actions that they're taking must be consistent with trying to do everything they can to prevent innocent Palestinian civilians from being hurt or killed or killed or missing.”
But smaller bombs have also caused collateral damage.
The first use of the GBU-39 in the current war was on October 24 in Khan Yunis, when two houses were hit with four bombs, one expert said.
In January, Israel struck the top two floors of a five-story residential building in Rafah just before 11 p.m. An Amnesty International investigation concluded that the bomb used in the strike was a GBU-39, killing 18 civilians, including four women and 10 children. This was one of a list of possible illegal uses of US weapons in Israel that Amnesty International outlined in April, dating back to January 2023.
The State Department concluded in May that Israel's failure to protect civilians in Gaza likely violated humanitarian standards, but said it had found no specific cases that would justify withholding U.S. military aid.
Current and former U.S. officials said Israel does not typically share information about its use of GBU-39s with the U.S. government, and a system the State Department created in August to track civilian deaths caused by U.S. weapons in foreign conflicts has struggled to compile a comprehensive list. One U.S. official said the May 26 airstrike in Rafah was being investigated as part of a new process to determine whether the use of U.S. weapons violated humanitarian law.
Israel has deployed the GBU-39 since 2008, using it in Gaza, Syria and Lebanon. The bomb has a range of at least 40 miles and is GPS-guided, with specific target coordinates set before launch. Experts say the GBU-39 is highly accurate and can hit specific rooms within a building.
The United States has delivered at least 9,550 GBU-39s to Israel since 2012, including an emergency order of 1,000 last fall, according to data from the Stockholm International Peace Research Institute, which tracks arms transfers. More shipments have probably been made since then, said Brobst of the Foundation for Defense of Democracies.
Most attack aircraft can carry up to eight GBU-39s at a time and guide each one independently to different targets, making it an effective weapon for the Israeli military, said NR Jenzen Jones, director of the Weapons Research and Services Agency.
But when it comes to reducing civilian casualties, “it's not a panacea,” Jensen-Jones said. “It may be small compared to other aerial bombs, but even a small diameter bomb packs a significant punch.”
Myra Noveck contributed reporting from Jerusalem, Eric Schmidt From Washington.