While Israel may monitor activity at the Rafah crossing, it has no physical presence there and no control over whether or not it is open. When Egypt wants it closed, for their own reasons, they use the excuse that the required EU monitors aren't there, and the EU's excuse is that their mission is to coordinate withFatah crossing guards...and Fatah is long gone. Here is an article from an Israeli source, which is probably biased, on the supply issue.