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A cross-domain solution (CDS) is an accredited controlled interface that provides the governed ability to manually or automatically access and transfer information between separate security domains of different classification levels, enforcing filtering and policy so only authorized data crosses.
Last updated: October 19, 2026
Why it matters to your mission. Mission data that a decision depends on is scattered across networks of different classification levels, and the classified pieces cannot legally or technically touch the unclassified ones without controls. A cross-domain solution is the accredited path that moves or exposes only the authorized data across that boundary, under enforced policy. The outcome is that a commander can act on a complete picture instead of the fraction that happened to live on one network.
A cross-domain solution (CDS) is an accredited controlled interface that provides the governed ability to manually or automatically access and transfer information between separate security domains of different classification levels, enforcing filtering and policy so only authorized data crosses. It is sometimes shortened to "cross domain" and overlaps in casual use with "guard" and "data diode," though those name narrower mechanisms. In Department of Defense usage, any transfer of data between security domains must run through an accredited CDS rather than an ad hoc connection.
The boundary a CDS governs is not a convenience. It is the line between what the government has decided may be seen on each network, and crossing it incorrectly can expose classified information or admit a threat into a protected enclave. That is why a CDS is not a router with a filter bolted on; it is an accredited system with its own assurance requirements, and the reasoning that decides what may cross has to be as inspectable as the decision it supports.
Mission data is partitioned by classification by design. Command-and-control data is frequently highly classified because it reveals the location of friendly forces and the disposition of an adversary, so it lives on networks that unclassified and coalition systems cannot reach. The U.S. Government Accountability Office found that these classification barriers cause some of the largest data-sharing delays across the Department's command-and-control effort, and that once information is marked restrictively it is difficult to change even when the marking is too tight (see the U.S. Government Accountability Office, GAO-25-106454, Defense Command and Control, 2025).
That partitioning collides with how operations work. A targeting cell, an air-operations center, and a coalition partner may each hold a piece of the same situation at a different level, and the decision needs all of them. Combined Joint All-Domain Command and Control (CJADC2) depends on reconciling data across exactly these boundaries. The cross-domain solution is the sanctioned place where that reconciliation is allowed to happen, so it carries a disproportionate share of the mission's risk and value. Get it right and a distributed force sees the same thing in time to act; get it wrong and either the data never arrives or the wrong data leaks.
Define a CDS by what it enforces, not by a single product shape. Most accredited deployments combine several of these functions:
The accreditation around these functions is the point. A CDS is approved by the responsible authority against a defined assurance standard before it is allowed to connect two domains, and that approval is what distinguishes it from any other network connection.
The terms get used as if they were interchangeable. They are not. A data diode is one mechanism a CDS may use; a CDS is the accredited system that governs the whole transfer.
| Dimension | Data diode | Cross-domain solution (CDS) |
|---|---|---|
| What it is | A hardware-enforced one-way link | An accredited system that governs transfer or access between domains |
| Direction | Physically one-way only | One-way or bidirectional, by policy |
| Content inspection | Little or none; it only enforces direction | Filters, validates, and inspects content against policy |
| Decision logic | Fixed in hardware | Policy-driven, auditable, and updatable within accreditation |
| Accreditation | A component inside a larger design | The accredited system approved to connect the domains |
| Typical use | Guaranteed one-way feed, such as sensor data up | Access and transfer across classification levels with content control |
A data diode answers "which direction." A cross-domain solution answers "which specific data, under what policy, with what record." A diode can be part of a CDS; it is not a substitute for one.
A CDS exists because networks are accredited to carry information up to a specific level and no higher. In the cloud, the Department's official impact levels run from IL2 and IL4 for unclassified data to IL5 for sensitive unclassified and national-security-system information, and IL6 for information classified up to SECRET, which must run on dedicated, isolated infrastructure rather than commercial cloud (see the Defense Information Systems Agency, DoD Cloud Computing Security Requirements Guide, via the DoD Cyber Exchange). Information above SECRET is handled on separate systems outside those cloud impact levels. A cross-domain solution is what allows controlled movement between these otherwise isolated levels, which is why the number and sensitivity of the domains it bridges drive how much assurance it must carry.
A cross-domain solution controls whether data may cross a boundary. It does not, on its own, make the data that arrives usable. That second problem is where Torch.AI's reasoning infrastructure fits. Torch.AI builds government-owned reasoning infrastructure that connects to mission data where it lives and prepares it for movement and reasoning across environments of different classification levels, without displacing the systems of record it came from.
The data-availability layer, ORCUS, handles multi-source ingestion, normalization, and lineage, so that data carrying its classification and provenance can be presented to an accredited cross-domain path in a form the path can inspect and a receiving analyst can trust. NEXUS makes that data meaningful through semantic representation and reusable knowledge domains, and HALO fuses the relationships across it into a graph an analyst can reason over. Because the reasoning layer preserves provenance and classification markings end to end, every element that crosses a domain keeps a traceable line back to its source, which is exactly what a reviewer needs to defend a cross-domain transfer.
Torch.AI's role is to complement the accredited CDS, not to replace it: the CDS enforces what may cross, and the reasoning layer makes what crosses coherent and defensible on the other side. You can see how this is packaged as a capability on the Torch.AI software page. This capability is also the bridge to cross-domain data integration, the broader problem of making multi-level data usable once it has moved.
When evaluating how data will move and become usable across classification boundaries, require the following:
Scoping a cross-domain capability? Bring these seven requirements to a scoping call and we will walk each one against your environment and classification boundaries: request a technical walkthrough.
Because mission data is partitioned by classification and the pieces a decision needs often live on networks that cannot legally or technically reach each other. A CDS is the accredited path that moves or exposes only the authorized data across that boundary, which the Government Accountability Office identifies as one of the hardest and most delay-prone parts of integrating command-and-control data.
It enforces direction, filters and validates content against policy before anything crosses, separates inspection logic from the data path in high-assurance designs, and logs every transfer so it can be audited. It is an accredited system approved against a defined assurance standard, not a router with a filter.
A data diode is a hardware-enforced one-way link that controls direction only; a cross-domain solution is the accredited system that governs which specific data may cross, in which direction, under what policy, with a record. A diode can be a component inside a CDS, but it is not a substitute for one.
It moves data between networks accredited to different levels. In the cloud, the Department's impact levels run from IL2 and IL4 (unclassified) to IL5 (sensitive unclassified) and IL6 (classified up to SECRET on dedicated infrastructure), with information above SECRET handled on separate systems. A CDS enables controlled movement between these otherwise isolated levels.
No. A CDS controls whether and how data may cross a classification boundary. Cross-domain data integration is the broader problem of making that multi-level data coherent and usable once it has moved. The CDS enforces the crossing; the reasoning layer makes the result defensible.
Yes. In Department of Defense practice, any transfer of data between security domains must run through a cross-domain solution that has been accredited by the responsible authority against a defined assurance standard, rather than through an unapproved connection.
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Describe the problem.
Define the constraints. We will structure the session.
No demo.
No slide deck.
Real work.
