WASHINGTON, May 23 (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 ( BA ) 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 ( BA ) has said the weapon can defeat some jamming,

one of the sources said it would take Boeing ( BA ) months to fix.

Boeing ( BA ) and Ukrainian authorities did not immediately respond

to a request for comment.

The bomb is made jointly by SAAB AB and Boeing ( BA ),

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. "