Glancing through the munitions in the article, HIMARS were originally developed and deployed in the 90s, not sure if they have a backup to GPS.
Thr Excalibur system mentioned does have an inertial guidance system to fall back on but I would assume it would lose some precision that GPS would afford.
Russia’s ability to combat the high-tech munitions has far-reaching implications for Ukraine and its Western supporters — potentially providing a blueprint for adversaries such as China and Iran — and it is a key reason Moscow’s forces have regained the initiative and are advancing on the battlefield.
While other news accounts have described Russia’s superior electronic warfare capabilities, the documents obtained by The Post include previously unreported details on the extent to which Russian jamming has thwarted Western weaponry.
“The Excalibur technology in existing versions has lost its potential,” the assessments found, adding that battlefield experience in Ukraine had disproved its reputation as a “one shot, one target” weapon — at least until the Pentagon and U.S. manufacturers address the issue.
In a conventional war, the U.S. military might not face the same difficulties as Ukraine because it has a more advanced air force and robust electronic countermeasures, but Russia’s capabilities nonetheless put heavy pressure on Washington and its NATO allies to continue innovating.
But even before the United States ceased deliveries, Ukrainian artillerymen had largely stopped using Excalibur, the assessments said, because the shells are harder to use compared with standard howitzer rounds, requiring time-consuming special calculations and programming.
Senior Ukrainian military officials said Storm Shadow air-launched cruise missiles, provided by Britain, are less susceptible to Russian jamming because they do not rely solely on GPS but two other navigation systems, including an internal map that matches the terrain of its intended flight path.
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