The phrase "tahaluf siyasi" is very famous among Muslims who are involved actively in Muslim's Body or Movement in various field; politics, education, economy and others. Well, tahaluf siyasi from my understanding is a mutual understanding made by Muslims and others including non-muslims to face same enemies or hoes...
Muslim scholars viewed differently about this issue. For example, Sheikh Muhammad Qutb dan al-Syeikh al-Imam Abu Nasr Muhammad bin Abdullah said that we are not allowed to cooperate with non-muslims with any reasons, while Yusuf al-Qaradhawi , Dr Mustoffa al-Tohhan , al-Syeikh Muhammad Ahmad al-Rasyid , Doktor Solah al-Showi dan Doktor Munir Ghahdban said as a muslim, we can do some sort of agreement, or build cooperation with non-muslims by using evidences from Seerah of our Prophet Muhammad (pbuh.A very good example is the cooperation and unique relationship betweeen Prophet Muhammad (pbuh) and his non-muslim uncle, Abu Thalib. Abu Thalib took care of him after Abdul Mutalib died. He never compromises with other non-muslims who wanted to kill our Prophet though he was offered with lots of things. Next, we can see many agreements made by Rasulullah with Jewish, Bani Khazaah, King Najasyi, Bani Hashim and so on.
In my opinion, it is not wrong to cooperate with non-muslims. However, we should use and optimize well the benefits that we get from that cooperation, assuring everything is done because of Allah. Currently, in our country, we can see again that kind of cooperation especially made by political parties. For instant, PAS (parti Islam semalaysia) cooperate with DAP and PKR which are dominated by non-muslims and secular muslim. Next, PAS also opens its membership to non-Muslims called Dewan Penyokong PAS mostly joined by non-muslims. UMNO (known as pure malay political party) combined with MCA, MIC, and other non-muslim political parties.
The questions are, which party (UMNO or PAS) fully utilised the conditions that Islam wanted when they do Tahaluf Siyasi....wallahualam