sentences:  The Azerbaijani military doctrine adopted in 2010 allows for foreign military bases in Azerbaijan, and that action opened the way to speculation that Turkey could quarter its troops in the Nakhchivan region, an Azerbaijani exclave surrounded by Armenia and Turkey.Azerbaijan maintains a base in Nakhchivan that has received heavy Turkish support in the past, but no official information is available about the current scope of military cooperation between the two countries in the exclave.On the eve of the April 2009 official visit to Turkey by US President Barack Obama, sources in Ankara and Yerevan announced that a deal may soon be struck to reopen the border between the two states and exchange diplomatic personnel.