  A model system of equations has been derived to describe a toroidally
rotating tokamak plasma, unstable to Resistive Wall Modes (RWMs) and metastable
to Neoclassical Tearing Modes (NTMs), using a linear RWM model and a nonlinear
NTM model. If no wall is present, the NTM growth shows the typical
threshold/saturation island widths, whereas a linearly unstable kink mode grows
exponentially in this model plasma system. When a resistive wall is present,
the growth of the linearly unstable RWM is accelerated by an unstable island: a
form of coupled RWM-NTM mode. Crucially, this coupled system has no threshold
island width, giving the impression of a triggerless NTM, observed in high beta
tokamak discharges. Increasing plasma rotation at the island location can
mitigate its growth, decoupling the modes to yield a conventional RWM with no
threshold width.
