Major threats to homeland security include: the threat of biological weapons, cyber terrorism, internet recruitment of terrorists, along with homegrown terror and international terrorism. Biological terrorism is especially worrisome, because terrorists can use organic materials to create significant damage. They may make use of bacteria, viruses or other toxic materials to create epidemics within a large space. Among the agents which may be used for bioterrorism are: anthrax; viruses including Ebola, smallpox and Lassa; Yersinia pestis and ricin, all of which are potentially lethal.

It is important to secure airports, ground transportation systems, and critical infrastructure. To do this, it is essential for architects, designers and airport administrators to coordinate with local and federal law enforcement in new construction and remodeling plans.
Efforts should be made to keep distance between employees and members of the public, and potential hazards. Baggage Flow and the flow of people should be separated. Security systems should consist of a combination of mobile patrols and fixed posts. Concealed areas should be kept to a minimum and all assets should be monitored, including the following: aircraft, utilities, communications systems, roadways, access ways, support and storage, facilities, members of the public, employees and fuel areas.

Barriers should also be kept between members of the public and surveillance equipment.
Loading docks and mailrooms should be located away from passengers. Dedicated ventilation systems should be employed to combat biohazards. HVAC intakes should be made as inaccessible to the public as possible.

Counterterrorism is – to some degree – the responsibility of public law enforcement, as well as other actors. It is essential that counter terrorism involve coordination among state, local and federal authorities as well as private citizens. Because terrorism is often homegrown, law enforcement officers in every city ought to be prepared for the possibility of a terror attack. Although federal authorities can often provide assistance, it is often up to local agencies to act as the first responders to an event. They can follow up on citizen reports of suspicious activity, mobilize emergency vehicles and respond to a limited number of threats. On the other hand, public law enforcement officers are not equipped to handle ever counter-terror measure. They do not have access to the global intelligence resources of organizations such as the FBI or the CIA. Because many acts of terror are fostered in nations other than the one in which they take place, public law enforcement cannot be involved in every step of prevention. Law enforcement partners in other nations, as well as intelligence agencies and even military actors may need to cooperated in order to effectively prevent and respond to acts of international terror.

Trends in private and public security include a greater focus on interagency and intergroup collaboration. Private security entities and local law enforcement now work together at a much higher rate than they did in the past. Public and private security entities are also making greater use of social media a law enforcement tool. Social networking sites such as Facebook have often provided public and private security entities with information that makes it much easier to track the movements of suspects and family members than traditional methods once made it. Security entities are also placing a greater emphasis on staff education.

Security agencies are also moving away from simply addressing crimes that have already been committed and focusing on crime prevention. They have begun to encourage community participation in law enforcement and are working hand-in-hand with community organizations to address suspicious behavior and the conditions that cause crimes. Both private and public security entities are making use of strategies such as crime mapping and engaging in intelligence-led policing.