NATO Secretary-General Anders Fogh Rasmussen is expected to meet with Armenia's leadership during a two-day visit to Yerevan that begins on September 5.
The visit comes amid escalating tensions between Armenia and neighboring Azerbaijan over Azerbaijani President Ilham Aliyev's decision to pardon an Azerbaijani military officer who had been jailed for life in Hungary for the murder of an Armenian officer in 2004.
Hungary says it returned the officer to Azerbaijan after receiving assurances from Azeri officials that his life sentence would be enforced.
It is not clear if the NATO chief will visit Azerbaijan, with NATO saying only that Rasmussen is opening a regional tour of the South Caucasus.
Armenia and Azerbaijan have been in conflict for around three decades over Nagorno-Karabakh, the Armenian-controlled territory inside Azerbaijan.