This letter describes a new strategy for initiating a chemical reaction that is based on the laser-induced breakdown of a nanoscopic barrier, which physically separates the reactants in space. Because the breakdown of the barrier is fast (similar to0.3 mus) and owing to the nanometer dimension of the barrier, the reactants can be brought together and the reaction can be initiated rapidly. The time scale most suited for this method (from microseconds to tens of milliseconds) bridges nicely between the faster time scales that are accessible mostly with laser-based triggering experiments and the slower time scales that are studied most frequently with flow-based devices.