1. Justice is a By Product of Character. You can not have Justice in land without having Character level of a nation raised.
2. Conquering other nations has nothing to do with Justice of Character.
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Those days are gone that your Prophet could write letters to the Kings and Emperors of the world and threaten them to 'Convert to Islam, Pay Protection Money (Jiziyah) or face Wrath of Allah (our attack)' because neither we are 'Wrath of Allah', nor much stronger Super Powers of the world are going to let us conquer other nations or themselves.
If Allah had not damned us in 898 A.D. for following our Mollaas and letting them destroy our Character instead of following Him only, we still would have been the most advanced and the most powerful of the world. He had even proven that He had damned us and we were not on His Path anymore by letting 'QraamTaiyn' of tiny little Bahrain demolish 'Kaabaa' and take Hajray AswaD to Bahrain in 923 A.D. but we did not understand, what He was saying to us. He had let QraamTaiyn use Kaabaa as their Toilet, rape Daughters of Meccans in Kaabaa Compound and He had let them. He had let them rule for a whole century but we could not understand.
How else could your God tell you that you were on Satanic Path instead of His?
Then, He tried again to make you understand and let Mongols sack Baghdad and build Mounds of your Cut Heads and you did not understand.
Then, He tried again to make you understand and let your own Moslim Amir Taimoor sack Baghdad and build Mounds of your Cut Heads again and you did not understand.
Then, dismayed with Arabs, he raised their virtual Slave Saljooq Turks to become Super Power of the World as Ottoman Empire (SulTanTay Osmaniya Turkiya) but when they started walking path of Satanic Mollaas, He ended their Empire.
He raised, a 14 years old Descendant of Taimoor and Changaiz Khan to start Mogul Empire but when you let Mollaa Auragnzeb become your Emperor, He destroyed your Mogul Empire.
Dismayed by all Moslims, He raised more Humane European Powers to enslave you so, you could learn to be better Humans but when He freed you from them, you became more Characterless corrupt Savages instead of straightening out your act. Why cry Justice and for Omar now, when you have reduced your status to the lowest of Human Beings ...?
You are born to eat, shit, drink, piss, make babies and die giving nothing back to Humanity just like Animals. Since you have become a Shame for Allah and His Prophet, why should you not be slaughtered and eaten just like you eat Animals instead of given another chance by Him, God's Damned people ...?  
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S U Trukman