The fusion reaction between deuterium and tritium takes places:

To carry out fusion of two nuclei, they must be brought very close to each other so that they overcome the repulsive force. This is only possible at a temperature nearly equal to 10⁷ K. Hence, the fusion reaction between deuterium and tritium takes place at very high temperature and high pressure.

As fusion can occur at very high temperatures, the fusion reactions are also knows as thermonuclear reaction.