Hi Clownshack
The analysts at the Global Firepower Index (GFI) incorporate all facets of a country: population, economy, geography, naval forces, etc.
If nuclear-armed Israel is ranked at 15, the GFI analysts have probably considered population size as a factor, meaning the ability to absorb casualties and field reservists. Israel's population and armed forces size is much smaller than Iran's or Turkiye's. In a long term conflict, Iran and Turkiye can outlast many countries.
Also, Israel's high-tech economy may be good at making them money, but that won't help them if those civilians are called into military service.
The Gaza pogrom began taking its toll on their economy.
Israel's maritime capabilities are sufficient for local defense, but for offensive operations far away from port I'm not sure.
Lastly, other countries can survive with embargoes and being cut off from food supplies. Israel might be vulnerable in that respect.
Which countries would drive in food for them? They have angered all their neighbors. Israel had to beg some European countries for help when they had troubling battling wildfires last year.
For similar reasons, non-nuclear powered South Korea is ranked at 5; nuclear-armed North Korea is 31.
The GFI is meant to be a reference tool to quickly get a picture of a country's military power, that's all.
