The presidents of Kazakhstan, Kyrgyzstan, Tajikistan and Uzbekistan met in Astana for the first time in nine years to 'solve developing problems together'.
The transition from opposition to co-operation could create favourable conditions for resolving many regional problems, analysts say.
The US government continues to support the development of Kazakhstan's health and education sectors, said Wren Elhai, US embassy spokesperson in Astana.
Kazakhstan produced a documentary about the successful results of President Nursultan Nazarbayev's January 16-18 visit to Washington.
Uzbekistan is demonstrating its readiness to support the Afghan government's effort to build a peaceful future, officials and specialists say.
The US and Kazakhstani presidents discussed the enhanced strategic partnership between Astana and Washington and resolved to strengthen co-operation on political and security issues.
The US and Central Asian nations share key strategic interests such as countering terrorism and improving regional stability, says a top US diplomat.
Central Asian nations will increase co-operation this year, with leaders potentially meeting for the first time since 2005, Kazakhstani political scientist Erlan Karin predicts.
Central Asian security, bilateral trade and infrastructure development were among the topics during Afghan President Ashraf Ghani's visit to Tashkent earlier this month.
The leaders of the two countries oversaw the signing of dozens of agreements and trade contracts worth more than $500 million.