Convert USD yield into EUR yields

I want to calculate the EUR equivalent yield from the USD yield curve. For example : how to translate the USD libor curve into an EUR equivalent yield curve ?

Do I need to use FX forwards or is the X-CCY basis enough ?

$$P^\mathrm{EUR}_\mathrm{USD\ Libor\ 3m}(T) = P^\mathrm{USD}_\mathrm{USD\ Libor\ 3m}(T) \frac{fx(T)}{fx(0)}$$