A history of nuclear hotlines and an overview of the CATALINK initiative
The CATALINK Brief
The CATALINK communications system is an internationally-driven, secure, and resilient communications solution that has the potential to avert catastrophes amidst rising tensions between adversaries. CATALINK would build on the “hotline” model of previous generations, and rely on open-source technologies to maximize user integrity and trust.
The CATALINK Components
CATALINK is a novel approach to a modern, hotline-style crisis communication system that allows leaders of nuclear-armed states to communicate with each other – built to be secure, resilient, and trusted from the silicon up.
The Puck
A simple, secure, and robust device meant for dedicated communication between global leaders and officials during a nuclear crisis or other high-stakes event, like disaster response. Designed on an open-source platform, it will send trusted messages in minutes.
The Broker
An interface between the Puck and the ROCCS, which determines the path of the Puck message throughout the desired network. The Broker will switch networks as needed, including between satellites, commercial networks, fiber-optic lines, and high-frequency or low-frequency radio bands. If/when all other options fail or are compromised, it can fall back to the ROCCS mesh network.
The ROCCS
Resilient Omni Frequency Crisis Communications System
A permanently active network that utilizes multiple channels and wavelengths to ensure reliable relays of Puck messages. The ROCCS is one of a variety of redundant networks through which the Puck messages may travel, depending on availability, the threat environment, and the type of message sent.
Origins of CATALINK
The concept for CATALINK emerged during a workshop the Institute for Security and Technology (IST) convened at Stanford University’s Hoover Institution in 2019. The workshop, hosted in collaboration with Stanford’s Preventive Defense Project and the Nautilus Institute for Security and Sustainability, brought together multinational nuclear policymakers, academics, current and former senior decision-makers, and experts from the technology sector for discussions on global nuclear communications. Participants highlighted the technical vulnerability of communication systems–and discussed the potential solutions that could reinforce resilience and trust. A synthesis report from that workshop can be read here.
The unique combination of policymakers and technologists was critical to CATALINK’s origins. Today, that same mix continues to be a crucial source of advice and development for the blueprint of the CATALINK system.
Eric Grosse, former Vice-President, Security Engineering in Google has been instrumental in designing and developing the code of the Puck, and the code of Puck is accessible in open-source platforms like Github.
Why are crisis communications important to nuclear risk reduction?
Any use of nuclear weapons, intentional or accidental, could have catastrophic consequences that impact all global citizens, not just those in nuclear-armed states. To reduce the risk of catastrophe we must provide decision-makers with every possible offramp. Crisis communications have historically been an essential tool to provide redundant and reliable channels of trust and security between nuclear-armed states, allowing for explanation, warning, and negotiation. Thus, nuclear-armed states need every possible tool available to promote trust, confidence, and accountability for nuclear risk reduction measures.
Nuclear-armed states, non-nuclear-armed states, and civil society organizations have frequently emphasized the importance of crisis communications in reducing nuclear escalation risks, and many highlight the need to enhance the resilience and number of connections between states. As stated in a variety of documents from the United Nations, the United States government, and coalitions of non-nuclear states, the consensus is clear: the world needs more secure multilateral hotlines. CATALINK could serve as a blueprint for what these improved channels could look like.
2019
“Nuclear-Weapon States to improve or establish crisis communication and protocol among each other, e.g. by hotlines and risk reduction centres.”
“…the nuclear-weapon States commit to the following immediate measures:… To create and enhance effective crisis prevention and management tools, including notification and data exchange agreements, enhanced leader-to-leader and military-to-military contact, the establishment of crisis-proof communication lines and risk reduction centres.”
2025
“We should also partner with regional governments and businesses to build scalable and resilient energy infrastructure, invest in critical mineral access, and harden existing and future cyber communications networks that take full advantage of American encryption and security potential.”
History of Nuclear Hotlines
After the world came to the brink of nuclear war during the Cuban Missile Crisis in 1962, the United States and the Soviet Union agreed that the two superpowers did not have the ability to communicate effectively and swiftly in moments of crisis. To address this issue, officials set up the first nuclear direct communication link (DCL), or “hotline” between American and Soviet leaders in June 1963.
Building on the success of the US-Soviet direct line, other nuclear-armed states like France, the United Kingdom, India, Pakistan, and China later established various political and military leadership crisis communication channels with other nuclear and non-nuclear-armed states. States later adopted domain-specific hotlines such as the US-Russia and US-China space and cyber links.
For a full account of all direct political and military links between nuclear-armed states, view IST’s Atlas of Crisis Communications.
Frequently Asked Questions
Learn more about CATALINK, the technical specifications, how it fits in the strategic landscape, and what’s next for the effort
What is CATALINK?
The CATALINK project builds an open source, additive, multilateral crisis communication technology for use by the leaders of nuclear weapons states. If implemented, CATALINK would build on the “hotline” model of previous generations, and rely on internationally-driven open-source technologies to maximize user integrity and trust.
What are the CATALINK components?
The Puck
A simple, secure, and robust device meant for dedicated communication between global leaders and officials during a nuclear crisis or other high-stakes events like disaster response. Designed with an open-source platform, the Puck will send text messages in minutes.
The Broker
An interface between the puck and the ROCCS which determines the path of the Puck message throughout the desired network.
The ROCCS (Resilient Omni Frequency Crisis Communications System)
A permanently active global mesh network, the ROCCS uses multiple channels/wavelengths to ensure reliable message relays; one of a variety of redundant networks for puck messages to use depending on availability, the threat environment, and the type of message sent.
Why is CATALINK needed?
Not every country with nuclear weapons has a direct leader or military communication line with every other country with nuclear weapons. Additionally, there are no multilateral hotlines between states with nuclear weapons. Unlike the Cold War when security concerns were largely focused on one bilateral conflictual dyad, 21st century challenges are increasingly complex with multiple strategic competitors. CATALINK is an additive measure, not meant to replace existing hotlines but to add other resilient options for leaders to communicate before, during, and after a conflict or nuclear war.
Existing hotlines may be vulnerable to kinetic threats, such as environmental degradation or destruction during conflict, or non-kinetic threats such as cyber attacks and electronic warfare. New technological developments that could further destabilize communications (e.g. AI-generated audio and video) must also now be taken into account when thinking of how to improve resiliency, especially in a degraded security environment where miscommunication and misperceptions can flourish.
Staff & Advisors
The team continues to drive progress on developing a blueprint for a last-resort, secure crisis communications channel
From the Field
Hear what our team, advisors, funders, and officials have to say about the CATALINK initiative