The Atlantic meridional overturning circulation (AMOC) is a basin-scale oceanic circulation system that redistributes heat and freshwater between low and high latitudes, exerting a fundamental control on global climate. Studies suggest that AMOC variability on decadal time scales is linked to varying strength of deep-water formation at high latitudes, which occurs in the Labrador Sea, Irminger Sea, and Nordic Seas. However, the relative contributions from individual basins to the decadal AMOC variability and their potential interconnections remain highly uncertain. Using the annual output from a 320-year pre-industrial control simulation of a high-resolution coupled model, we find that AMOC variability is mostly attributed to density anomalies in the Irminger Sea, compared to that in the Labrador and Nordic seas. Furthermore, such density anomalies in the Irminger Sea have contributions from the Nordic and Labrador seas, mainly through advection along the boundary current or the interior pathway. We will further discuss the role of temperature and salinity in producing the density anomalies leading to subpolar AMOC variability, and how they will change in response to global warming.