Capability to fill inertial confinement fusion (ICF) targets with DT has recently been established at the Weapons Engineering Tritium Facility (WETF) at Los Alamos National Laboratory (LANL). The target filling system provides DT-filled glass targets for the U.S. National ICF Program. Tritium storage, purification, mixing, analysis, and high pressure capabilities at WETF are used to provide DT at pressures up to 400 atm to a target filling cell that can operate at temperatures to 400 °C. Isotopically pure tritium is obtained from the Tritium Systems Test Assembly at LANL, and typically has purities of 99% tritium or better. At WETF, a palladium-silver diffuser is used for removal of decay 3He from tritium prior to mixing with deuterium. After preparation, DT mixtures are stored in a passivated volume to minimize impurity accumulation from stainless steel. Analysis of tritium and DT mixtures is performed with a quadrupole mass spectrometer/beta scintillation detector system that utilizes an analytical technique previously developed at LANL to provide hydrogen isotope, helium, and impurity analysis. Glass targets are filled in aluminum eggcrates. The target filling cell has been designed to contain two eggcrates while maintaining isothermal conditions across the eggcrates during diffusion filling of targets. Results from a cryogenic condensation technique performed at Lawrence Livermore National Laboratory have confirmed the fill pressures.