Russian jamming may have hamstrung a US-made bomb kit being used in Ukraine, leaked documents say

• Leaked Pentagon documents highlighted concerns about the Joint Direct Attack Munition weapon.
• The American-made bomb kit used by Ukraine may have been hamstrung by Russian jammers.

A US-made bomb kit that has been used by Ukraine's military may have been hindered by Russian signal jamming, leaked Pentagon documents reveal.

Highly sensitive US intelligence documents recently circulated around the internet and on various social media platforms and are now at the center of a major federal investigation. Dozens of these secret documents contain detailed information about the ongoing war in Ukraine, including each side's combat capabilities and battlefield updates.

One document in particular highlights concerns about US-made bomb kits which have been sent to Ukraine in recent months. The document is titled "Why are JDAM-ERs Failing? BDA From Recent Strike?" and has markings that show it is secret in nature and not to be revealed to any foreign governments.

JDAM-ER refers to an extended-range variation of the Joint Direct Attack Munition, which is a kit that converts existing unguided bombs into precision-guided munitions. A new tail section, which includes an inertial navigational system (INS) and a global positioning system (GPS), is added to the bomb to make it more accurate in any weather condition. This air-to-surface weapon navigates to its target autonomously once it's released from an aircraft.

One JDAM kit costs just over $24,000 and are used for bombs weighing between 500 and 2,000 pounds, according to a US Navy fact sheet. The range is 15 miles, though that jumps to 45 miles with the extended variant.

The leaked intelligence document on the JDAMs reviews several issues that this weapon has faced on the battlefield in Ukraine and outlines two factors potentially explaining why there have been "duds and/or misses." One factor is the bomb fuses aren't arming at their release, which Ukraine's air force has worked to fix.

The other factor, according to the document, is that suspected Russian GPS jamming has gotten in the way of JDAM-ER operations and has caused some misses, which it says has happened before with Ukraine's guided multiple launch rockets (GMLRS).

"However, the Director of the Joint Navigation Warfare Center (JNWC) stated based on their analysis, GPS jamming should not have affected the JDAM-ER strikes based on target location compared to active Russian jammers, but other factors may have prevented the JDAM-ER from acquiring GPS signal," the Pentagon document notes.

At the time of the document's publication — which, for many of the documents that were leaked, is late February or early March — Ukraine's air force had dropped at least nine JDAM-ER bombs against Russian targets, but four of them appear to have missed due to Russian jamming. The confidence in this particular assessment was medium to high. The document recommended neutralizing the jammers as before JDAM-ERs are used for best results.

Insider was not able to independently verify the contents of the document. Neither the Pentagon, nor Ukraine's embassy in Washington DC, immediately responded to Insider's request for comment on the findings outlined.

The leaked US intelligence about the JDAM-ER is part of a trove of documents that were posted online in recent weeks and contain highly sensitive and classified military information about US allies, like Israel and South Korea, and its adversaries, like Russia, Iran, and China. Experts have described the leaks as one of the most significant intelligence breaches in decades.

But the documents also contain a significant amount of information about Russia's ongoing war in Ukraine, including detailed casualty estimates and force attrition rates for both sides, as well as intelligence about Ukraine's combat readiness, battlefield preparations, weapons, stockpiles, maps, and more.

The Pentagon documents first became public last week and circulated through social media platforms like Discord, Twitter, and Telegram. Because the military information included in the documents is, in many cases, top secret, it has triggered widespread alarm, anger, and criticism in Washington and its partner countries.

A Pentagon official shared a statement with Insider explaining that the Department of Justice has opened a criminal investigation into the leaks and that there is an interagency effort focusing on the potential affect that the documents may have on US national security and that of its allies.

When asked during a press conference on Monday if the leak was contained and whether or not it's an ongoing threat, White House National Security Council spokesperson John Kirby responded: "We don't know. We truly don't know."

Chris Meagher, the assistant to the secretary of defense for public affairs, told reporters on Monday that the Secretary and Department of Defense and the larger United States government "take this apparent unauthorized disclosure extremely seriously and this is a top priority for us."