All perfect praise be to Allah, The Lord of The Worlds, and may His peace and blessings be upon our Prophet Mohammad and upon all his family and companions.
Al-Aqsa Mosque (Farthest Mosque) is the Mosque located in the Holy City of Jerusalem, and it enjoys a special status in Islam since Allah has mentioned it in the Noble Quran where He said, "Glory to (God) Who did take His servant for a Journey by night from the Sacred Mosque to the farthest Mosque, whose precincts We did bless,- in order that We might show him some of Our Signs: for He is the One Who heareth and seeth (all things)." {Al-Isra`, 1}. And what a great honor this is!! It is the first Qibla Muslims prayed towards and the third sanctuary.
The Messenger of Allah (PBUH) made it amongst the three Mosques for which a journey should be undertaken where he said: "Do not undertake a journey to visit any Mosque, but three: this Mosque of mine, the Mosque of al-Haram and the Mosque of Aqsa (Bait al-Maqdis)."{Related by Bukhari & Muslim}.
As for Al-Aqsa Mosque being a sanctuary, a sanctuary, in the sight of Allah and His righteous slaves, is the place which is sacred and blessed. Just as a Muslim honors the Mosque of Al-Haram in Mekka and the Prophet`s Mosque in Madina, he/she must also honor Al-Aqsa Mosque (Bait al-Maqdis) since Allah has blessed it and its precincts where He said, " the farthest mosque whose precincts We did bless." {Al-Isra`, 1}.
Multiplication of the reward for praying at Al-Aqsa Mosque is a clear manifestation that Allah has blessed and honored it. Along these lines, Prophet Mohammad (PBUH) said: " One prayer in Al-Haram Mosque is better than one hundred thousand prayers in any other mosque, one prayer in my Mosque is better than a thousand prayers in any other mosque and one prayer in Bait Al-Maqdis (Al-Aqsa Mosque) is better than five hundred prayers in any other mosque" {Narrated by al-Baihaqi in Shu`ab Al-Eiman}.
In conclusion, Al-Aqsa Mosque is a sacred place for all Muslims, so honoring and defending it is an obligation. In addition, the fact that it is blessed was established in the Noble Quran and the Holy Hadith. And Allah knows best.