The training will take place in Tajikistan at a US-funded regional training centre designed to prevent trafficking in nuclear materials and WMDs.
International leaders expressed outrage and urged a 'strong' response after the latest alleged use of chemical weapons by the Kremlin-backed Syrian regime.
Access to the ports of Aktau and Kuryk will allow the United States to set up an alternative route to Afghanistan, bypassing Russia.
Independent investigations have dismissed the Kremlin's assertion that Wagner Group mercenaries are volunteers not affiliated with the Russian military.
The Russian-backed Syrian army has continued to violate the terms of a ceasefire in Eastern Ghouta, where more than 1,300 civilians, a fifth of them children, have been killed in recent weeks.
Indiscriminate airstrikes and use of barrel bombs, and the deployment of chemical weapons, have killed more than 900 civilians, including at least 179 children, since mid February.
The United States is working with Central Asian partners to improve security throughout the region and to ensure long-term stability.
The Russian president's saber rattling was just an attempt to sound tough ahead of national elections, observers say.
Russia does not have 'a custom of interfering in the internal affairs of other countries and is not doing so now', Kremlin spokesman Dmitry Peskov told reporters. Simple facts belie the statement.
Officials from law enforcement and security forces of both countries reviewed prospects for co-operation in the fight against extremism and terrorism.