Units of US troops evacuated from Iraq have been diverted to positions in Jordan opposite a Syrian tank concentration building up across the kingdom's northern border, debkafile reports.The incoming US contingents are housed at the King Hussein Air Base of al-Mafraq, 10 kilometers from the Syrian border. They are the first US boots to hit the ground directly opposite Assad's army, brought there by Bashar Assad's threat to set the Middle East on fire if the pressure against him persists.