Initially, Siper Block 2 will provide only limited capabilities for defending against ballistic targets. Full-scale ballistic missile defense capabilities will not be achieved until Siper Block 3 is implemented. For this reason, NATO has so far assumed responsibility for defending against ballistic threats.
I’m afraid that isn’t entirely reflecting the complete picture.
Siper block 2, as you say, should provide limited defence capabilities against ballistic threats. But in essence it is a 150+km range, 30km altitude single stage missile specifically designed to intercept high altitude UAVs, jet fighters, cruise and air to ground missiles. So as you point out should give some cover against SRBMs.
The Siper 3 version will have a range of 180-200km, and more than 30+km altitude and is designed to intercept ballistic missiles in their high terminal phase. Similar to Pac-3/MSE.
But to intercept MRBM and higher range ballistic missiles that may carry nuclear warheads, we need exo atmospheric interceptors like SM3. These have altitudes and ranges as high as 1000km and 2500km respectively depending on the version.
SM-3 Variant Capabilities:
- Block IA/IB:
- Range: Approximately 700 km to 1,200 km.
- Max Altitude (Ceiling): Approximately 500 km (311 miles).
- Block IIA:
- Range: Over 1,200 km (some reports indicate up to 2,500 km).
- Max Altitude (Ceiling): 900 km to over 1,000 km
These missiles cost between 10million to 30 million dollars each depending on the version being used. (4 interceptors NATO used to defend our airspace should have cost in excess of 40 million dollars at least - that is if they used a single interceptor per target as quite often two interceptors are used to positively eliminate)
So, Siper-3 is not the real remedy. It is a partial patch.
To intercept positively and surely those MRBMs Iran has been using against us, we really need exo atmospheric interceptors.
EDIT :
When multiple threats were targeted in Iran operation, 1.5 SM3s per target were fired to be sure.