Wa `alaykum As-Salamu wa Rahmatullahi wa Barakatuh.
In the Name of Allah, Most Gracious, Most Merciful.
All praise and thanks are due to Allah, and peace and blessings be upon His Messenger.
Dear questioner, thanks for your trust in us. May Allah reward you abundantly for your enthusiasm to know the teachings of your religion. We invoke Almighty Allah to protect all suffering people all over the world against oppression and injustice.
Islam is the religion of mercy. It does not sanction injustice whether inflicted against Muslims or non-Muslims. Also, Islam teaches that Muslims are one brotherhood like one body; when an organ aches, all other organs share the pain with fever and insomnia. In his Hadith, the Prophet (peace and blessings be upon him) stated: “A Muslim is a brother of a Muslim. He must not wrong him, nor fail him, nor hand him over (to enemies).” In doing so, a Muslim should stick to the Islamic teachings and do only what is lawful from the Islamic point of view.
In his response to the question in point, Sheikh Faysal Mawlawi, Deputy Chairman of the European Council for Fatwa and Research, states:
"I would like to say that once Iraq is attacked by the US, as the latter is threatening to do, jihad becomes an individual obligation on all Iraqi people. Also, it becomes incumbent on all neighboring Muslim countries until they push back the American enemy. Because of the partition of the Muslim and Arab world into different countries, while all of them are subject to different interests and conditions, fighting is no longer possible for all countries. Consequently, the obligation moves to helping and assisting the Iraqi people by all possible means, whether this assistance be in the form of financing, the media, or political backing. The faintest help we can offer is supplication and condemning such attack.
Finally, it is to be noted that every Muslim knows what he/she can offer to help his fellow brethren in Iraq while they are engaged in a battle that is imposed on them."
You can also read:
Does Attacking Iraq Warrant Targeting US Interests?
Muslims’ Role in the Prospective War on Iraq