ITER is aiming for 150.000.000K. Please note that this temperature of the plasma, i.e. average kinetic energy of the ions is in electron volts
For example, a typical magnetic confinement fusion plasma is 15 keV, or 170 megakelvins .
15 KeV is enough to assure that the plasma does not neutralize itself and the bare nuclei have a high enough statistical and quantum mechanical probability of interaction/fusion by overcoming the coulomb repulsion of two positive nuclei.
The electrostatic force between the positively charged nuclei is repulsive, but when the separation is small enough, the attractive nuclear force is stronger. Therefore the prerequisite for fusion is that the nuclei have enough kinetic energy that they can approach each other despite the electrostatic repulsion.
The temperatures necessary for the various fusion reactions:
The fusion reaction rate increases rapidly with temperature until it maximizes and then gradually drops off. The DT rate peaks at a lower temperature (about 70 keV, or 800 million kelvin) and at a higher value than other reactions commonly considered for fusion energy.