by Frida Ghitis, The Miami Herald, USA - President-elect Barack Obama has so far said nothing about the war raging between Israel and Hamas in Gaza because he has nothing to gain and much to lose by making his position clear. His silence, which he defends deferring to President Bush -- ''We have only one president at a time'' -- is not exactly a shining example of courage and leadership. Instead, it reveals once again a man defined more by caution than boldness. And one who knows just how much is at stake for the Middle East and for his own administration.