For a long time phonons have been regarded to be irrelevant to high temperature superconductivity (HTSC). However, our recent measurements of phonon dispersion in YBCO with neutron inelastic scattering at MAPS of the ISIS and of electron dressing of phonons by x-ray inelastic scattering at the APS suggest otherwise. They show that the in-plane Cu-O bond-stretching mode interacts strongly with electrons, reflecting the SC order parameter, and the electronic structure is strongly anisotropic in the Cu-O plane. The results are consistent with the formation of a short-range stripe structure and a resonant vibronic state. We conjecture that the spin-charge stripe structure brings down the electronic energy scale close to those of phonons, creating the resonant condition. A model based upon overscreening of phonons by charge and formation of the vibronic state yields a SC transition temperature over 300K. While this magnitude may not be accurate it suggests that the phonons are likely to be closely involved in the mechanism of HTSC.