Leaders of the Collective Security Treaty Organization (CSTO) are gathering in Tajikistan's capital for a summit.
The presidents of Armenia, Belarus, Kazakhstan, Kyrgyzstan, and Russia are scheduled to arrive in Dushanbe on September 14.
The summit is scheduled for September 15, a day after the presidents hold separate meetings to discuss ties.
Tajik authorities have beefed up security in the capital as a special operation to locate and arrest former Deputy Defense Minister Abduhalim Nazarzoda and his followers continues.
Nazarzoda is wanted for allegedly masterminding attacks on police in and near Dushanbe earlier in September.
The summit's agenda includes the election of the organization's secretary-general and the head of its united headquarters.
Armenia is expected to take over the one-year presidency in the CSTO from Tajikistan.