Field-induced nanopore wetting by aqueous solutions, including electrolytes, provides opportunities for a variety of applications. Con!icting porosity requirements have so far precluded direct implementations of a two-way control: the pores have to be su ciently wide to allow water in#ltration at experimentally relevant voltages but should not exceed the kinetic threshold for spontaneous expulsion in the absence of the #eld. Applicable widths are restricted below a few nanometers. Only a narrow window of #elds and pore geometries can simultaneously satisfy both of the above requirements. Accurate accounts of wetting equilibria and dynamics at nanoscale porosity require molecular level descriptions. Here we use molecular dynamics simulations to study dynamic, #eld-controlled transitions between nanocon#ned liquid and vapor phases in contact with an unperturbed aqueous or electrolyte environment. In nanopores wetted by electrolyte solutions, we observe depletion of salt compared to the bulk phase. The application of a local electric #eld enhances the uptake of water and ions in the con#nement. In systems prone to capillary evaporation, the process can be reversed at su cient strength of the electric #eld. For alternating displacement #eld, we identify the conditions where O (ns) responses of the reversible in#ltration/ expulsion cycle can be secured for experimentally realizable #eld strengths, porosity, and salinity of the solution