Praise be to Allaah.
Taking the kaafirs as friends (muwaalaah) means supporting them and helping them in matters of kufr, such as the Muslims fighting alongside the kuffaar, such as when the kaafirs launch an assault against a Muslim country and a Muslim befriends them and supports them and helps them in fighting against that country, whether that is with weapons or by supplying them with anything that will help them to fight the Muslims. This is muwaalaah, or a type of friendship that is haraam, because it means joining them and supporting them against other Muslims.
With regard to seeking their help, that depends of the purpose to be served. If that serves the Muslims’ interests, there is nothing wrong with it, on the condition that we must beware of their evil and treachery and there be no risk of them betraying us. But if that serves no interest then it is not permissible to seek their help because there is no good in them.
Liqaa’aat al-Baab al-Maftooh by Shaykh Muhammad ibn Saalih al-‘Uthaymeen, p. 20.
Source : Islam Q&A