President Félix Tshisekedi has instructed the army chief to establish recruitment centres across the country in response to Rwandan “aggression” - a reference to claims that Kigali is militarily supporting the March 23 Movement (M23) rebel movement in DR Congo's eastern Nord-Kivu province.
Mr Tshisekedi made the remarks in a national address on Thursday.
He said he was responding to the appeal by the Congolese youth who “have been expressing their desire to protect the territorial integrity” against threats by “some neighbouring countries”.
He urged them to "organise themselves into vigilance groups" to support the army.
The president added that diplomatic efforts to ease tensions with Rwanda had failed.
He repeatedly accused Rwanda of backing the M23 rebels, who have been involved in a series of clashes with the Congolese army since May.
Rwanda has denied supporting the rebels.