All of the investigated peptides facilitated very rapid ion transport, but indolicidin is particularly interesting as it is both unstructured and inserted only peripherally, making it highly unlikely to form structural pores. However, even at a conservative peptide:lipid molar ratio of 1:50, indolicidin facilitated near complete equilibration within 100 ms. We have previously shown experimentally that indolicidin significantly increases the rate of lipid flip-flop in these membranes, and MD simulations revealed that the peptide induced lipid flipping creates transient aqueous channels that allow ions to pass throughout the membrane . Hence, these transient pores emerge as a likely mechanism and, based on the MD simulations, a diffusion model was fitted to the experimental kinetic data, revealing that a small number of transient pores can readily describe the salt permeabilization kinetics. The present work shows that, in the case of indolicidin and LL-37, well-defined structural pores are neither supported by the structural characterization, nor needed to explain the salt permeabilization kinetics. Instead, transient pores resulting from AMP induced lipid flip-flop, which are in line with Wimley's interfacial activity model and in excellent agreement with the present results and several previous studies, appear far more likely. The present work provides important answers regarding the molecular mechanisms of some of the most researched antimicrobial peptides. Additionally, the methodology presented here can readily be applied to other peptide-membrane systems. We believe this can greatly aid in the substantial efforts currently being undertaken to understand and utilize AMPs as promising novel antibiotics. assistance provided at the BM29-BioSAXS beamline. Also at ESRF, we thank the PSCM lab for their support. We gratefully acknowledge ILL for neutron beam time on the D22 instrument. We acknowledge the use of the Norwegian Centre for X-ray Diffraction, Scattering and Imaging (RECX), supported by the RCN. We are very grateful for the assistance and help given by Thomas Vogelaar and Henrik Torjusen during the beamtimes.