Recently, cyber attacks against public communications networks are getting more complicated and varied. Moreover, in some cases, one country could make systematic attacks at a national level against another country to steal its confidential information and intellectual property. Therefore, the issue of cyber attacks is now regarded as a new major threat to national security. The conventional way of operating individual information security systems such as IDS and IPS may not be sufficient to cope with those attacks committed by highly-motivated attackers with significant resources. In this paper, we discuss the technologies and standard trends about actual cyber threat and response methods, design the collaborative response framework based on the security information sharing in the inter-domain environments. The computation method of network threat level based on the collaborative response framework is proposed. The network threats are be quickly detected and real-time response can be executed using the proposed computation method.