Both countries are seeking to establish a long-term presence in Syria to further their own economic and political interests.
Uzbekistani President Shavkat Mirziyoyev has sacked Rustam Inoyatov, chief of the National Security Service.
The Kremlin has often used military aid as a means of exercising influence, with the goal of keeping countries -- in particular those in Central Asia -- dependent on Russia.
The move aims to "decentralise power in Uzbekistan", analysts say.
Securing a land route from Tehran to Beirut would enable the Iranian regime to funnel arms and fighters across the entire region, experts say.
Tashkent is seeking to ensure safe handling of future disasters and crises.
Tajikistan and the OSCE have been conferring annually since 2007 on development priorities.
Even if they want to leave, war-torn Syria has become a trap.