diff --git a/src/cli.ts b/src/cli.ts
index 2acb8e3..3d96b70 100644
--- a/src/cli.ts
+++ b/src/cli.ts
@@ -9,8 +9,13 @@ const program = new Command();
 program
   .command("run")
   .description("process all images")
-  .action(async () => {
-    await run();
+  .option(
+    "--delete",
+    "Delete output images that dont have a matching input image"
+  )
+  .action(async (options: { delete?: boolean }) => {
+    const { delete: deleteUnmatched } = options;
+    await run(deleteUnmatched);
   });
 
 program
diff --git a/src/run.ts b/src/run.ts
index 492fd02..b937a3e 100644
--- a/src/run.ts
+++ b/src/run.ts
@@ -4,7 +4,7 @@ import { logger } from "./logger";
 import { getClient, deleteFilesBulk } from "./s3";
 import { buildState } from "./state";
 
-export const run = async (): Promise<void> => {
+export const run = async (deleteUnmatched?: boolean): Promise<void> => {
   try {
     const config = getConfig();
     const { bucketName, inputConfig } = config;
@@ -17,7 +17,7 @@ export const run = async (): Promise<void> => {
 
     await processImages(state, inputConfig, bucketName);
 
-    if (state.unmatchedOutputImages.length > 0) {
+    if (state.unmatchedOutputImages.length > 0 && deleteUnmatched) {
       logger.info("deleting unmatched output images");
       await deleteFilesBulk(bucketName, state.unmatchedOutputImages);
     }