The UN and the Collective Security Treaty...
It was signed by UN Secretary General Ban Ki-moon and CSTO General Secretary Nikolai Bordyuzha.
Ban said the declaration was an important step for the UN to consolidate cooperation with regional organizations.
The CSTO, which is made up of Armenia, Belarus, Kazakhstan, Kyrgyzstan, Russia, Uzbekistan and Tajikistan, has held observer status at the UN since 2004.
Russian Foreign Minister Sergei Lavrov said Moscow was interested in closer cooperation with the UN through the CSTO, especially in combating serious problems like drugs trafficking, especially from Afghanistan.
"Drugs trafficking has emerged as a threat to both regional and international peace and security," he said.
Russia has repeatedly called for the CSTO"s peacekeeping potential to be used more widely.
Russian business daily Kommersant said UN-CSTO cooperation might cover such areas as conflict prevention and resolution, terrorism, international crime and arms trafficking.