diff --git a/app/api/events/[id]/route.ts b/app/api/events/[id]/route.ts
index 33597ff..21a8e54 100644
--- a/app/api/events/[id]/route.ts
+++ b/app/api/events/[id]/route.ts
@@ -2,6 +2,8 @@ import { NextRequest, NextResponse } from "next/server";
 import { getServerSession } from "next-auth/next";
 import { authOptions } from "@/app/api/auth/options";
 import { prisma } from "@/lib/prisma";
+import { deleteMicrosoftEvent } from "@/lib/services/microsoft-calendar-sync";
+import { logger } from "@/lib/logger";
 
 // Helper function to check if user can manage events in a mission calendar
 async function canManageMissionCalendar(userId: string, calendarId: string): Promise<boolean> {
@@ -45,10 +47,20 @@ export async function DELETE(req: NextRequest, props: { params: Promise<{ id: st
   }
 
   try {
-    // First, find the event and its associated calendar
+    // First, find the event and its associated calendar with sync config
     const event = await prisma.event.findUnique({
       where: { id: params.id },
-      include: { calendar: true },
+      include: { 
+        calendar: {
+          include: {
+            syncConfig: {
+              include: {
+                mailCredential: true
+              }
+            }
+          }
+        }
+      },
     });
 
     if (!event) {
@@ -77,7 +89,41 @@ export async function DELETE(req: NextRequest, props: { params: Promise<{ id: st
       }
     }
 
-    // Delete the event
+    // If event has externalEventId and calendar has Microsoft sync, delete from Microsoft too
+    if (event.externalEventId && event.calendar.syncConfig && event.calendar.syncConfig.provider === 'microsoft' && event.calendar.syncConfig.syncEnabled) {
+      const syncConfig = event.calendar.syncConfig;
+      const mailCredential = syncConfig.mailCredential;
+      
+      if (mailCredential && mailCredential.use_oauth && mailCredential.refresh_token) {
+        try {
+          await deleteMicrosoftEvent(
+            session.user.id,
+            mailCredential.email,
+            syncConfig.externalCalendarId || '',
+            event.externalEventId
+          );
+          
+          logger.info('Successfully synced event deletion to Microsoft', {
+            eventId: params.id,
+            externalEventId: event.externalEventId,
+            email: mailCredential.email,
+          });
+        } catch (syncError: any) {
+          // Log error but don't fail the request - local deletion will proceed
+          // Don't disable syncConfig for permission errors (403) - user just needs to re-authenticate
+          const isPermissionError = syncError.response?.status === 403;
+          logger.error('Failed to sync event deletion to Microsoft', {
+            eventId: params.id,
+            externalEventId: event.externalEventId,
+            error: syncError instanceof Error ? syncError.message : String(syncError),
+            isPermissionError,
+            suggestion: isPermissionError ? 'User needs to re-authenticate with Calendars.ReadWrite scope' : undefined,
+          });
+        }
+      }
+    }
+
+    // Delete the event from local database
     await prisma.event.delete({
       where: { id: params.id },
     });
diff --git a/app/api/events/route.ts b/app/api/events/route.ts
index 52488d8..ed49874 100644
--- a/app/api/events/route.ts
+++ b/app/api/events/route.ts
@@ -2,7 +2,7 @@ import { NextRequest, NextResponse } from "next/server";
 import { getServerSession } from "next-auth/next";
 import { authOptions } from "@/app/api/auth/options";
 import { prisma } from "@/lib/prisma";
-import { updateMicrosoftEvent } from "@/lib/services/microsoft-calendar-sync";
+import { updateMicrosoftEvent, deleteMicrosoftEvent } from "@/lib/services/microsoft-calendar-sync";
 import { logger } from "@/lib/logger";
 
 // Helper function to check if user can manage events in a mission calendar
@@ -263,10 +263,14 @@ export async function PUT(req: NextRequest) {
           });
         } catch (syncError: any) {
           // Log error but don't fail the request - local update succeeded
+          // Don't disable syncConfig for permission errors (403) - user just needs to re-authenticate
+          const isPermissionError = syncError.response?.status === 403;
           logger.error('Failed to sync event update to Microsoft', {
             eventId: id,
             externalEventId: existingEvent.externalEventId,
             error: syncError instanceof Error ? syncError.message : String(syncError),
+            isPermissionError,
+            suggestion: isPermissionError ? 'User needs to re-authenticate with Calendars.ReadWrite scope' : undefined,
           });
         }
       }
diff --git a/lib/services/microsoft-calendar-sync.ts b/lib/services/microsoft-calendar-sync.ts
index e230b7f..9cbf96e 100644
--- a/lib/services/microsoft-calendar-sync.ts
+++ b/lib/services/microsoft-calendar-sync.ts
@@ -448,6 +448,54 @@ export async function updateMicrosoftEvent(
   }
 }
 
+/**
+ * Delete a Microsoft calendar event via Graph API
+ */
+export async function deleteMicrosoftEvent(
+  userId: string,
+  email: string,
+  calendarId: string,
+  eventId: string
+): Promise<void> {
+  try {
+    const accessToken = await getMicrosoftGraphClient(userId, email);
+    
+    const url = `https://graph.microsoft.com/v1.0/me/calendars/${calendarId}/events/${eventId}`;
+    
+    logger.info('Deleting Microsoft event', {
+      userId,
+      email,
+      calendarId,
+      eventId,
+      url,
+    });
+    
+    await axios.delete(url, {
+      headers: {
+        Authorization: `Bearer ${accessToken}`,
+        'Content-Type': 'application/json',
+      },
+    });
+    
+    logger.info('Successfully deleted Microsoft event', {
+      userId,
+      email,
+      eventId,
+    });
+  } catch (error: any) {
+    logger.error('Error deleting Microsoft event', {
+      userId,
+      email,
+      calendarId,
+      eventId,
+      error: error instanceof Error ? error.message : String(error),
+      responseStatus: error.response?.status,
+      responseData: error.response?.data,
+    });
+    throw error;
+  }
+}
+
 /**
  * Sync events from Microsoft calendar to local Prisma calendar
  */
diff --git a/lib/services/microsoft-oauth.ts b/lib/services/microsoft-oauth.ts
index 172e400..a590a45 100644
--- a/lib/services/microsoft-oauth.ts
+++ b/lib/services/microsoft-oauth.ts
@@ -21,6 +21,7 @@ const REQUIRED_SCOPES = [
   'https://graph.microsoft.com/Mail.Read',        // Read mail via Graph API
   'https://graph.microsoft.com/Mail.Send',        // Send mail via Graph API
   'https://graph.microsoft.com/Calendars.Read',   // Read calendars via Graph API
+  'https://graph.microsoft.com/Calendars.ReadWrite', // Read and write calendars via Graph API (for updates/deletes)
 ].join(' ');
 
 /**