The old union

The concept of a Central Asian union emerged soon after the dissolution of the Soviet Union in 1991. Although all states acceded to the newly formed Commonwealth of Independent States (CIS), it was felt that more regional cooperation was needed.^[2] In early 1992, Tajikistan plunged into the Tajikistani Civil War (1992–1997) between government forces and various Islamist rebel factions supported by the Taliban; thus they could not participate in the integration process. Turkmenistan preferred to maintain neutrality, and decided not to partake in CIS or Central Asian integration.

The remaining three republics Kazakhstan, Kyrgyzstan and Uzbekistan signed a treaty on 23 September 1993 to create an economic union, which was followed by a proclamation of a "single economic space" on 10 February 1994, and the establishment of an Interstate Council with an Executive Committee on 8 July 1994. In theory, any CIS member state could join the Central Asian Union.^[3]

The Union was also given a military dimension. Still in civil war, Tajikistan joined the CAU as an observer in 1996.^[2] A Council of Defence Ministers was formed, and, under the aegis of the United Nations, a peacekeeping force was formed, which held its first training exercises on the territory of Kazakhstan and Uzbekistan in September 1997.^[3]

A new union

A new Central Asian Union was proposed by Kazakhstan President Nursultan Nazarbayev on April 26, 2007, in order to create an economic and political union similar to that of the EU encompassing the five former Soviet Central Asian republics of Kazakhstan, Kyrgyzstan, Tajikistan, Turkmenistan and Uzbekistan.

So far the presidents of Kazakhstan and Kyrgyzstan have signed an agreement to create an "International Supreme Council" between the two states. In addition, Kazakhstan, Uzbekistan and Kyrgyzstan have signed a Treaty of Eternal Friendship. Kazakhstan and Uzbekistan have also decided to set up a free trade zone.^[4]

Although the proposed new union had the support of the presidents of Kazakhstan, Kyrgyzstan and Tajikistan by 2008, it was outright rejected by former Uzbek president Islam Karimov.^[5] After Karimov died in 2016, however, the idea of integration was brought back on the table.

On 15 March 2018, a new Central Asian Summit was held in Astana between Kazakh President Nursultan Nazarbaev (host), Uzbek President Shavkat Mirziyoyev (initiator), Kyrgyz President Sooronbai Jeenbekov, Tajik President Emomali Rahmon, and Turkmen parliament speaker Akja Nurberdiýewa. The Kazakh President Nursultan Nazarbayev hosted the summit at the Aqorda Presidential Palace. It was the first summit of Central Asian leaders in nearly a decade.^[6] They resolved to henceforth convene every year in March before the Nowruz (New Year) holiday.^[7]

A second summit was held on 29 November 2019 in Astana.