By Igor Jovanovic for Southeast European Times in Belgrade – 05/07/06 Serbian soldier and a US Marine stand guard by the Serbian flag in front of Mig-21 airplane at the Batajnica military airport near Belgrade on 23 June. [Getty Images] Two US Air Force F-16s touched down at Belgrade's Batajnica military airport on 23 June, making an historic visit. It was the first time since World War II that American fighter jets have landed at a Serbian Air Force airport. According to the defence ministry, the event was part of efforts to improve military co-operation between Serbia and the United...