Sorry Mr Zanganeh Pakistan has support of a very powerful guy inside Iran and I don't think he will allow you to go to the international courts for suing Pakistan
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Iran-Turkey gas relationships
If I remember correctly we sued our Turkish brothers and won then they sued us in another case and they won right now its maybe 2-1 in favor of Turkey
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Both Iran and Turkey enjoy same level of HDI ( .76 -.77 ) . it means its completely halal to sue them in courts and take their precious Lira on the other hand its halal for them to sue us and take our precious gas because the gap between us is very close but its different between Iran-Pakistan case as you can see there is a meaningful gap between us in HDI . and as long as this gap exist talking about suing and stuff like this will not help .right now its duty of Iran to help Pakistan's economy grow .