It is not permissible for you to transgress against the property of this government even if they are kaafirs, because they have trusted you and have allowed you to enter their land on the basis of this trust, and you have promised to respect their trust and not betray it. Simply by entering their land you have given them this covenant and promise, otherwise they would not have allowed you to enter. The Muslim should not break his promise or covenant deceitfully or betray a trust. Allaah says (interpretation of the meaning):“And fulfil (every) covenant. Verily, the covenant will be questioned about”
“O you who believe! Fulfil (your) obligations”
And the Prophet (peace and blessings of Allaah be upon him) said: “The signs of the hypocrite are three: when he speaks he lies, when he makes a promise he breaks it, and when he is entrusted with something, he betrays that trust.” Agreed upon; narrated from Abu Hurayrah. Muslim added: “… even though he prays and fasts and claims to be a Muslim.”
And Allaah is the Source of strength. May Allaah send blessings and peace upon our Prophet Muhammad and his family and companions.