WASHINGTON (Reuters) - Russian jamming has kept many of Ukraine's relatively new long-range GLSDB bombs from hitting their intended targets, three people familiar with the challenges told Reuters.

Ukraine over the last year sought weapons with longer ranges than the 43 miles (69 km) of U.S.-provided GMLRS rockets so Kyiv could attack and disrupt Russian supply lines and muster points.

To answer that call, Boeing Co offered a new weapon to the Pentagon with a 100-mile (161-km) range, the Ground-Launched Small Diameter Bomb (GLSDB). The glide-bomb has small wings that extend its reach, and it is comprised of the GBU-39 Small Diameter Bomb (SDB) and the M26 rocket motor, both of which are common in U.S. inventories and relatively inexpensive.

But the GLSDB's navigation system, which enables it to be steered around obstacles like mountains and known anti-air defenses, has been targeted by Russian jamming, the three people briefed on he matter said.

While Boeing has said the weapon can defeat some jamming, one of the sources said it would take Boeing months to fix.

Boeing and Ukrainian authorities did not immediately respond to a request for comment.

The bomb is made jointly by SAAB AB and Boeing, and it was in development well before Russia's full-scale invasion of Ukraine in 2022.

Jamming happens when huge amounts of energy are broadcast into an area, overwhelming a device's signal. Russia has used the tactic on Ukrainian radios, drones and even GPS-guidable Excalibur 155 millimeter artillery munitions.

Ukraine has been using GLSDBs since earlier this year and experts have noted that it has not performed well on the battlefield because of jamming.

Ukraine has also been using both short and long range Army Tactical Missile Systems (ATACMS) which have a range up to 180 miles (300 km).

Jamming on the battlefield in Ukraine is "simply a reality, and numerous weapon systems have had to contend with these and other countermeasures," said Tom Karako, a weapons expert at the Center for Strategic and International Studies.

"Whether such challenges are in turn countered with technical upgrades or simply alternative methods of employment, the utility of long range fires is going to persist. "

(Reporting by Mike Stone in Washington; Editing by Cynthia Osterman)

By Mike Stone