khalil jahshan is the executive director of the arab center of washington, a non-profit organizationoster deeper understanding of arab culture. and natan sachs is a fellow at the saban center for middle east policy at the brookings institution. he focuses on israeli foreign and domestic politics and the arab-israeli conflict. welcome you both. natan saches, what can israel accomplish with i ground invasion that it couldn't accomplish by sending hundreds of missile. >> the pain objectives to go after the tunnels between gaza strip an israel. egypt has worked did-- there are tinls that gund neath the board tore israel an several attacks have come out of there, especially most famously an attack that abducted the israeli soldier and then there was five years of imprisonment. trying to go after these tunnels on the gaza side. >> woodruff: have they not been able, help us understand what it if about these tunnels, what is going on inside them or around them that israel can't accomplish with missiles. >> well, there is a lot you condition do from the air. they know a bit about where they a