OGADISHU, Somalia - Ethiopia sent fighter jets into Somalia and bombed several towns Sunday in a dramatic attack on Somalia's powerful Islamic movement, and Ethiopia's prime minister said his country had been "forced to enter a war." It was the first time Ethiopia acknowledged its troops were fighting in support of Somalia's U.N.-backed interim government even though witnesses had been reporting their presence for weeks in an escalating battle that threatens to engulf the Horn of Africa region. Ethiopian Prime Minister Meles Zenawi went on television to announce that his country was at war with the Islamic movement . ....