East Asia Maritime Monitor: User guide and methodology

The East Asia Maritime Monitor is an interactive dashboard providing visualizations of the latest ACLED data on maritime conflict and tension in the South China Sea, Taiwan Strait, East China Sea, and Philippine Sea. The monitor tracks military activity and coercive actions, as well as other non-military actions, around disputed features and boundaries in the South China Sea and Taiwan Strait from 1 January 2025 to present. 

How to use the dashboard

• Filtering events: Use the filters in the top left box to select actors, a 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) boundaries,¹ China’s “nine-dash line,” and the so-called First Island Chain. These layers can be toggled on or off using the controls in the bottom left box.
• Reading the map: Events are dynamically displayed as multicolored 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 and the Taiwan Strait. 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. 

_{Note: The interactive dashboard presents a subset of categories recorded for the South China Sea and the Taiwan Strait, 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 and the Taiwan Strait. For a comprehensive visualization of ACLED’s full regional coverage, users are encouraged to explore the data available through the ACLED Explorer platform.}
 

Locations

The dashboard is organized into three geographic areas. Each area covers both maritime and land-based events directly related to maritime conflict. 

• Taiwan Strait: covers the body of water separating Taiwan from China
• South China Sea: covers the semi-enclosed sea bordered by China, Taiwan, the Philippines, Vietnam, Malaysia, Indonesia, and Brunei, as well as disputed territories. 

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.