I'll proffer that NCIS would be the ideal "glue that binds" all other agencies. Civilian law enforcement up to the DOJ. Military law enforcement up to the DOD. International law enforcement above INTERPOL and up to treaty enforcement level.

With that in mind, there is also their website offering "Core Mission Areas" of NCIS. There are four listed, and I'll quote a bit from each.

Criminal Investigations (and it's subsections) https://www.ncis.navy.mil/About-NCIS/Core-Mission-Areas/Criminal-Investigations/

Throughout their careers, Special Agents are afforded the opportunity to work criminal investigations in offices located worldwide, in forward deployed environments, and with local, state, federal and international law enforcement partners.

Felony criminal investigations are the cornerstone of the NCIS mission. NCIS is the investigative entity within the Department of the Navy (DON) responsible for major criminal investigations involving Navy and USMC equities, service members, and affiliated civilian personnel. NCIS civilian Special Agents have the authority to investigate criminal acts in accordance with both the Uniform Code of Military Justice (UCMJ) and established criminal laws under the United States Code (USC) when there is a DON nexus.

Dedicated special agents in NCIS field offices worldwide initiate investigations and operations in cases of: child abuse child sexual violence child pornography family/domestic violence adult sexual assault stalking

Additionally, a close working relationship with other investigative agencies, federal and state prosecutors, forensic scientists, and the victim's family members are critical factors in a cold case unit's success.

Consistent with the NCIS mission to protect the Navy and Marine Corps, the NCIS Economic Crimes Department works to safeguard Department of Navy acquisition programs that enhance fleet readiness and respond to allegations of corruption, financial fraud, and illegal product substitution.

Types of Economic Crimes Investigated by NCIS:

Bribery Subcontractor kickbacks Antitrust Conflicts of interest Cost mischarging

Counterintelligence https://www.ncis.navy.mil/About-NCIS/Core-Mission-Areas/Counterintelligence/

Secretary of the Navy Instruction 3850.2E defines counterintelligence as "information gathered and activities conducted to identify, deceive, exploit, disrupt, or protect against espionage, other intelligence activities, sabotage, assassinations conducted for or on behalf of foreign powers, organizations, persons, or their agents, or international terrorist organizations or activities. " (SECNAV Instruction 3850.2E, January 3, 2017).

Within the Department of the Navy, NCIS serves as the coordinating authority of all DON CI activities, and is the only Department of Navy (DON) Component authorized to conduct investigations into actual, potential or suspected acts of espionage, sabotage, and intelligence activities conducted on behalf of foreign powers. *NCIS is also DON lead agency for the conduct of offensive CI operations, which seek to penetrate and neutralize adversary intelligence services. *

NCIS works to neutralize foreign intelligence services and foreign commercial activities seeking information about critical naval programs and research, development, test and evaluation facilities. The Research and Technology Protection (RTP) program works to safeguard the nation's vital defense technology through engagement and partnering with security and intelligence agencies.

Counterterrorism https://www.ncis.navy.mil/About-NCIS/Core-Mission-Areas/Counterterrorism/

Protecting the Naval forces from violent extremist organizations and individuals is one of NCIS' highest priorities. As the primary law enforcement and counterintelligence component for the Navy services, NCIS is focused on countering threats to the physical security of Sailors, Marines, and Department of the Navy civilian personnel and on preventing terrorist attacks against installations, ships, and expeditionary forces.

NCIS is responsible for detecting, deterring, and disrupting terrorism worldwide through a wide array of investigative and operational capabilities. Within the Department of the Navy, NCIS has exclusive investigative jurisdiction into the actual, potential or suspected acts of terrorism. ** NCIS accomplishes this through key partnerships** resulting in enhanced information-sharing of threats to DON for forces and assets. Offensive operations aim at identifying and interdicting terrorist activities. In defensive operations, NCIS supports key DON leaders with protective services and performs physical security assessments of military installations and related facilities—including ports, airfields, and exercise areas to which naval expeditionary forces deploy.

Cyber https://www.ncis.navy.mil/About-NCIS/Core-Mission-Areas/Cyber/

As more business, government, and social activities are conducted online, NCIS Cyber is responding to meet criminals where they operate—in cyberspace. NCIS Special Agents, computer scientists, investigative computer specialists, intelligence specialists, and contractors use NCIS Cyber capabilities to disrupt, deter, and mitigate criminal, terrorist, and foreign intelligence threats against the DON by:

Providing full-spectrum investigative and operational activities in the cyber domain

Coordinating with law enforcement and intelligence agencies in the U.S. and abroad

Conducting electronic media forensics

Tracking developments and trends in malware, phishing, and other computer intrusions

Countering cyber actors targeting data for exfiltration

In today's cyber threat environment, it is impossible for a law enforcement organization to combat cybercrime alone. To keep pace with emerging threats, technology, and crime trends, NCIS Cyber maintains strong relationships with local, state, Federal, and foreign law enforcement and intelligence agencies, as well as industry and academia, through partnership programs, subject matter expert exchanges, and capacity-building initiatives.

The point is that while NCIS mainly polices itself, it has been positioned as a clearing house for partnerships in these areas ranging from the state level to the treaty level.

This means if something was going to happen, NCIS would be the middle man between all parties. NCIS investigates a wide array of crimes within the DON, but also works with other partners to information share among all agencies.

So, if a big enough case came to pass. They would be a likely candidate to act as the middle man globally down to the city level.