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tokens: triggering of the radio nuclear activity, and detect in-falling molecular clouds that may accrete onto the SMBH. The ALMA observations of the 12 CO (2–1) line reveal that multiple clouds are distributed in a complex warped disk. Between 7.5 kpc and 2.5 kpc from the central radio AGN, the disk is oriented as the dust lane of the galaxy in the north-south direction ( PA ~ 180°). At inner radii (2.5 kpc – 700 pc), the disk changes slightly in orientation ( PA ~ 150°) and molecular clouds are found in proximity of dust ( Fig. 2 ) and of warm H 2 gas (see the left panel of Fig. 9 ). In the very central regions ( r ~ 700 pc), the disk changes abruptly its orientation and the molecular clouds form an edge-on circumnuclear disk oriented approximately east-west (PA ~ 72°). The carbon monoxide is a tracer of the cold phase of the molecular hydrogen. Depending on the conversion factor assumed, the total mass of cold molecular hydrogen is M (H 2 ) 3.2 × 10 8 –1.9 × 10 9 M ⊙ (see Table 3 ), while the circumnuclear disk has total mass of cold molecular hydrogen between 5.3 × 10 7 M ⊙ and 3.1 × 10 8 M ⊙ . The circumnuclear disk of molecular gas of PKS B1718–649 may form the reservoir of fuel for the radio emission. Although the rotation of the gas follows what is expected from the mass of the central SMBH and the distribution of the stellar body, the velocity dispersion of the gas is higher in the centre of the disk ( r 150 pc, 0.45′′) than at larger radii ( Fig. 7 ). This suggests that close to the radio source the gas may have non-circular orbits. The circumnuclear disk is also traced by the H 2 1-0 S(1) line emission ( Maccagni et al. 2016 ). The ratio between the column density of the H 2 gas traced by the H 2 1-0 S(1) line and by the 12 CO (2–1) line increases by a factor ten in the innermost 75 pc of the circumnuclear disk with respect to its outer regions (~ 110 and ~ 16, respectively). This suggests that, in the centre, the physical conditions of the molecular gas are different. It is possible that the radiative field of the AGN is photo-dissociating the cold component of the molecular gas, traced by the 12 CO (2–1) line, before the warmer component, traced by the H 2 1-0 S(1) line. This would indicate that the newly born AGN is actively changing the physical conditions of the surrounding ISM. Against the 230 GHz emission of the radio AGN, we detect 12 CO (2–1) gas in absorption (see Sect. 3.3 ). The absorption line has a width ( FWHM = 54 km s −1 ) much larger than the typical velocity dispersion of molecular clouds. Hence, either the absorption is tracing multiple clouds, or a single cloud with non-circular orbits, or a combination of both. The absorption line is detected at red-shifted velocities with respect to the systemic velocity (Δ v = +365 ± 20 km s −1 ). Its kinematics deviate from the rotation of the circumnuclear disk and the gas may be falling towards the radio source. At the same red-shifted velocities we also detect in emission a