The first 200 US soldiers are set to arrive in Bulgaria this autumn to test four military bases allocated to the upcoming 2,500-strong US contingent in the Balkan country, DPA REPORTED Thursday. The rest of the contingent could start arriving in early 2008 at the latest, Bulgarian media quoted US Ambassador to Sofia John Beyrle as saying. Sofia and Washington would meanwhile sign a series of documents regulating the conditions of stay of the US troops. Bulgaria and US agreed a year ago to share four military bases in the Balkans - two military airports, one training compound and one depot. The Americans would serve in Bulgaria on a six-month rotation. Bulgaria, a former eastern bloc country and NATO member since 2004, has been a staunch supporter of US policies, including the campaign in Iraq.