Methodology
South China Sea Monitor: User guide and methodology
A guide to navigating the South China Sea Monitor dashboard and understanding event categories and methodology underlying the data
The South China Sea Monitor is an interactive dashboard providing visualizations of the latest ACLED data on maritime conflict and tension in the South China Sea region. The monitor tracks military activity and coercive actions and other non-military actions around disputed features and boundaries in the South China Sea from 1 January 2025 to present.
How to use the dashboard
- Filtering events: Use the filters in the top left box to select actors, date range, and one or more event categories to display on the map.
- Map layers: By default, the map displays a layer featuring Exclusive Economic Zone (EEZ)1 boundaries and China’s “nine-dash line.” These layers can be toggled on or off using the controls in the bottom left box.
- Reading the map: Events are dynamically displayed as multicolor circles according to the subset filters selected, and sized according to the number of events recorded at that location. Click on any circle to view the event details.
- Tracking trends over time: Below the map, a bar chart displays weekly event counts for the filters selected.
Event categories
The dashboard visualizes four categories specific to this project, selected to capture events directly related to maritime conflict in the South China Sea. In ACLED’s dataset, these are coded under the Strategic developments event type.
Multiple categories may occur within the context of a single event. In such cases events are aggregated and coded to a single event under the highest category according to a hierarchy. For example, if the use of tear gas (Confrontation/Harassment) and a physical collision (Collisions) occur during the same event, the event will be categorized under Collisions on the dashboard because Collisions is a higher category in the hierarchy. The table below lists all event categories and hierarchy included in the dashboard.
| Category heirarchy | Dashboard category | Description |
|---|---|---|
|
1 |
Collisions |
Deliberate physical collisions or contact between vessels that result in damage. E.g., ramming and/or sideswiping |
|
2 |
Confrontation/Harassment* |
Confrontation: Use of tear gas, water cannons, flares, boarding of vessels, and seizure of any items or equipment Harassment: Non-violent activity at sea or in the air, including vessels chasing or intercepting each other, blocking maneuvers, use of horns, sirens, strobe lights, lasers, fire control radar, jamming of communications or transponder signals, near collisions, and arrests *This is a single category on the dashboard but split into two in the dataset |
|
3 |
Movement of forces |
Deployment of warplanes, navy ships, military buildup, construction on marine features, and maritime or air incursions into territory waters |
|
4 |
Military exercises |
Air and sea drills, Freedom of Navigation Operations (FONOP) exercises, live fire exercises |
Note: The interactive dashboard presents a subset of categories recorded for the South China Sea, with a specific focus on politically relevant developments such as military activities and coercive actions occurring around disputed features and maritime boundaries in the South China Sea. For a comprehensive visualization of ACLED’s full regional coverage, users are encouraged to explore the data available through the ACLED Explorer platform.
For more on how ACLED codes maritime locations and defines maritime boundaries, see this Data update: Improved maritime locations in ACLED's global dataset.
For general information on ACLED’s methodology and data collection process, see the ACLED Codebook on the Knowledge Base.
Footnotes
- 1
Boundaries have been modified to cover only the area of the South China Sea and are based on international law that has been challenged by various states. When claims overlap, an equidistance principle is used to define the border. For more, see Flanders Marine Institute's methodology.
