Ben Chia

[Theresa Fallon @TheresaAFallon]

Zoom in on the top shelf 👀

[Ben Chia @benbenchia]

Multiple differences from a regular trailer, which could be detectable from the air

[OSINTWarfare @OSINTWarfare]

A destroyed Shahab-3 Medium-Range Ballistic Missile (MRBM) launcher somewhere in the vicinity of Tehran.

Around the launch trailer, one can see remnants of the distinctive frame used by the IRGC to disguise missile launchers as regular trucks.

However, it seems this doesn't significantly hinder Israeli intelligence from identifying real launchers and subsequently targeting them with airstrikes. Naturally, in the process, regular trucks mistakenly identified as missile systems are also inevitably hit.

[Ben Chia @benbenchia]

We do not get to see ‘peacetime CEP’ , only CEP-net-of-GNSS-effects

[Dr. Jeffrey Lewis @ArmsControlWonk]

.@sam_lair and I estimated the "circular error probable" (CEP) of the most accurate Shahab-3 variant, the Emad, demonstrated in Iran's March 2024 missile strike. We estimated the CEP at ~1.2 km. That means whatever a Shahab-3 hits, Iran was most likely aiming at something else.

[Ben Chia @benbenchia]

GNSS effects may be the largest single component of the observed CEP for Iran’s newer missiles.

It is implausible that Iran would take any conv missile with a ‘peacetime CEP’ (ie without GNSS effects) of >100 meters to series production

[Decker Eveleth @dex_eve]

Also, lost in this conversation is the fact that Iran heavily uses GNSS guidence, which the Israelis are going to jam. That will degrade accuracy.

[Ben Chia @benbenchia]

3/
In the short term, the extent of GNSS-dependence in Iran’s missile and drone inventory is pretty much baked in. Aggravated by any aerodynamic control surfaces that have been added.

The remaining freedom of action is the disable or defeat the denial.

[Ben Chia @benbenchia]

1/
If Iran’s missiles are missing targets due to Israel’s GNSS denial, then in Iran’s next attack, Iran would be looking to disable those Israeli GNSS jamming/spoofing transmitters as the first step.

[Ben Chia @benbenchia]

2/
Alternatively, establish alternative and temporary GNSS service in the target areas, just prior to the arrival of GNSS-dependent weapons, that operate in domains not jammed/spoofed by Israel

Surely IDF has thought of this and has countermeasures in place

[Prof. Devi Sridhar @devisridhar]

From the 5 March to 2020 to 5 May 2023, almost **230,000 British people** died of COVID. Look at those two large waves before vaccines became available. Let's not let certain politicians erase what happened, and what a massive once-in-a-lifetime crisis and loss of life this was.

[Ben Chia @benbenchia]

@shashj …and the debate over ‘CEP’
is merely a proxy for that.

No one disputes ‘observed’ or ‘effective’ CEP *was* in the region of ‘useless against most military targets (conv)’

But premature to call that the functional limit of this weapons system

[Ben Chia @benbenchia]

@shashj I interpret the Nevatim results as Israel successfully created conditions where the attacking missiles were outside of design parameters.

OP himself theorized GNSS denial.

I think the controversy is whether safe to assume future performance will be just as dismal or not.

[Ben Chia @benbenchia]

When GNSS is working, the missile corrects for any drift as part of its reentry and terminal maneuvers.

But in the GNSS degraded or denied environment, it is flying blind and may feel nostalgic for the ballistic paths of old, with only brief exposure to that nasty atmosphere

[Ben Chia @benbenchia]

The alleged maneuvering / lifting body features of the newest missiles like the Fattah-2 would aggravate their inaccuracy in a GNSS degraded environment

Drift from catching 15 kph breeze alone is 4 m/s x say 30 s = 120 m

[Decker Eveleth @dex_eve]

@shashj Combination of longer range and likely GNSS denial.

[Ben Chia @benbenchia]

@dex_eve Figure the developed part of the base is about 3% buildings? (30,000 out of 1 mln sqm)

It would be improbable that out of the 1.1-2.5 sqm southern CEP ellipse, one of 16 missiles impacts a building.

[Ben Chia @benbenchia]

1/5
I am not sure about assumption of just two targets at Nevatim. This assumption is the basis for the CEP
estimate.

If the target set was actually several locations within the base, such as multiple HAS, with 2-3 missiles assigned to each, the CEP estimate may drop.

[Ben Chia @benbenchia]

@dex_eve I agree that it’s hard to make sense of the observed impact points at Nevatim.

However impacts like the one pictured suggest to me that it wasn’t a random scattershot of 3 dozen 0.6-0.9 km CEP missiles.

[Ben Chia @benbenchia]

@dex_eve To clarify #4, if you have N missiles and X targets and a SSPK of P, if you aim all N missiles at the same target, you will destroy at most 1 target but with high certainty.

If N > X and you aim them at different targets, you can expect to destroy at least X times P on average

[Ben Chia @benbenchia]

5/5
Having said all that, it could still be that that the two dozen missiles aimed at Nevatim were really intended to destroy two targets. We just don’t know, and the possible application of EW really muddies the waters.

Very interesting and valuable contribution from @dex_eve