diff --git a/specification/network/resource-manager/Microsoft.Network/stable/2020-03-01/firewallPolicy.json b/specification/network/resource-manager/Microsoft.Network/stable/2020-03-01/firewallPolicy.json
index b3f020ae08c8..856ee28bbed1 100644
--- a/specification/network/resource-manager/Microsoft.Network/stable/2020-03-01/firewallPolicy.json
+++ b/specification/network/resource-manager/Microsoft.Network/stable/2020-03-01/firewallPolicy.json
@@ -614,6 +614,10 @@
         "threatIntelMode": {
           "description": "The operation mode for Threat Intelligence.",
           "$ref": "./azureFirewall.json#/definitions/AzureFirewallThreatIntelMode"
+        },
+        "intrusionSystemMode": {
+          "description": "The operation mode for Intrusion system.",
+          "$ref": "#/definitions/FirewallPolicyIntrusionSystemMode"
         }
       },
       "description": "Firewall Policy definition."
@@ -1054,6 +1058,18 @@
         }
       },
       "description": "Response for ListFirewallPolicyRuleGroups API service call."
+    },
+    "FirewallPolicyIntrusionSystemMode": {
+      "type": "string",
+      "description": "The operation mode for Intrusion system mode.",
+      "enum": [
+        "Enabled",
+        "Disabled"
+      ],
+      "x-ms-enum": {
+        "name": "FirewallPolicyIntrusionSystemMode",
+        "modelAsString": true
+      }
     }
   }
 }