Iraq unsettles US planners By Jonathan Marcus BBC defence correspondent at Central Command headquarters With the weather fast improving, US and British air attacks against the Republican Guard units south of Baghdad are moving into high gear. Military sources also say that US marines have pushed northwards closer to the town of al-Kut on the Tigris river. But the difficulties of fighting a multi-front war could well slow the pace of this military operation. Invading forces have not met the reception they were told to expect "The enemy we're fighting is different from the one we had war-gamed against,"...