These are ludicrous claims
Firstly, Nag actually used Israel's head seeker which failed in Rajasthan, your so wonderful Israeli seeker failed.
INDIAN ARMY ORDERS NAG ATGMS
battle-updates.com
Then DRDO developed a higher resolution IIR seeker (128 x 128) than the Israeli one(64*64). That also failed.
And then DRDO developed a 640x512 resolution seeker, which was tested in 2016.
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Furthurmore, why comparing Spike with MPATGM or even NAG. Firstly, NAG role is far far different than of Spike,
But your lovely Spike missile failed in Rajasthan trials, so how you claiming Israel is ahead in ATGMs, and claiming Spike as world best is laughable claim, they dont even use liquid cooled IIR seeker like in Javelin (which also failed).
Please start to some research before making such ludicrous claims.
All the imports failed trials. The army's requirement was too high for deserts, they can't help it, so they had to wait for technology to catch up for Nag, and the DRDO finally got it a few years ago.