For a long time， hostile close-in reconnaissance （HCR） against China by foreign countries has become increasingly fierce， and has been upgraded to the theoretical level of "deterrence by detection"， showing a systematic and intelligent development trend. The threat， efficiency mechanism， technical theory， cognitive limitations of HCR are analyzed， limitations and cognitive misunderstandings of traditional DHCR （denial of hostile approaching reconnaissance） operations are analyzed. Taking electronic reconnaissance and radar counter-reconnaissance in electronic warfare as examples， regaining the electromagnetic right in DHCR is focused both with denying the tasks of HCR operations， a new theory of active defense in electromagnetic domain is proposed， and combined with the DHCR， a new tactical operation type is proposed with name of CRJ， laying a theoretical foundation for the systematization of DHCR.