diff --git a/README.md b/README.md
index 127cb7f..1ed1b70 100644
--- a/README.md
+++ b/README.md
@@ -37,7 +37,7 @@ $ export PATH=$PATH:`pwd`/target/appassembler/bin
 ```bash
 $ coop --help
 USAGE
-  coop [-hV] [--human-readable] [--reverse-columns] [--show-header] [--verbose] [<uris>...] [COMMAND]
+  coop [-hV] [--human-readable] [--reverse-columns] [--show-header] [--verbose] [--region=<region>] <uris>... [COMMAND]
 
 List s3 paths recursively with content sizes.
 
@@ -49,9 +49,10 @@ E.g.
 
 
 PARAMETERS
-      [<uris>...]         Zero or more s3 URIs.
+      <uris>...           One or more s3 URIs.
 
 OPTIONS
+      --region=<region>   AWS region, default US_WEST_2.
       --human-readable    Format content sizes in binary multi-byte units.
       --show-header       Show column header row in output.
       --reverse-columns   Reverse the order of output columns.
diff --git a/src/main/java/com/github/heuermh/cooper/Cooper.java b/src/main/java/com/github/heuermh/cooper/Cooper.java
index 2720aea..26a1cad 100644
--- a/src/main/java/com/github/heuermh/cooper/Cooper.java
+++ b/src/main/java/com/github/heuermh/cooper/Cooper.java
@@ -30,6 +30,7 @@
 
 import picocli.CommandLine.Command;
 import picocli.CommandLine.HelpCommand;
+import picocli.CommandLine.ITypeConverter;
 import picocli.CommandLine.ScopeType;
 
 import software.amazon.awssdk.regions.Region;
@@ -63,6 +64,14 @@
 )
 public final class Cooper implements Callable<Integer> {
 
+    @picocli.CommandLine.Option(
+        names = { "--region" },
+        type = Region.class,
+        converter = RegionConverter.class,
+        defaultValue = "US_WEST_2"
+    )
+    private Region region;
+
     @picocli.CommandLine.Option(names = { "--human-readable" })
     private boolean humanReadable;
 
@@ -75,7 +84,7 @@ public final class Cooper implements Callable<Integer> {
     @picocli.CommandLine.Option(names = { "--verbose" })
     private boolean verbose;
 
-    @picocli.CommandLine.Parameters(index = "0..*", descriptionKey = "uris")
+    @picocli.CommandLine.Parameters(index = "0..*", arity = "1..*", descriptionKey = "uris")
     private List<String> uris;
 
     /** Logger. */
@@ -92,7 +101,7 @@ public final class Cooper implements Callable<Integer> {
     public Integer call() throws Exception {
 
         S3Client s3 = S3Client.builder()
-            .region(Region.US_WEST_2)
+            .region(region)
             .build();
 
         if (showHeader) {
diff --git a/src/main/java/com/github/heuermh/cooper/RegionConverter.java b/src/main/java/com/github/heuermh/cooper/RegionConverter.java
new file mode 100644
index 0000000..6bdd3ad
--- /dev/null
+++ b/src/main/java/com/github/heuermh/cooper/RegionConverter.java
@@ -0,0 +1,34 @@
+/*
+ * The authors of this file license it to you under the
+ * Apache License, Version 2.0 (the "License"); you may not
+ * use this file except in compliance with the License.  You
+ * may obtain a copy of the License at
+ *
+ *  http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+package com.github.heuermh.cooper;
+
+import picocli.CommandLine.ITypeConverter;
+
+import software.amazon.awssdk.regions.Region;
+
+/**
+ * AWS Region converter.
+ *
+ * @author  Michael Heuer
+ */
+//@Immutable
+final class RegionConverter implements ITypeConverter<Region> {
+
+    @Override
+    public Region convert(final String value) throws Exception {
+        return Region.of(value);
+    }
+}
diff --git a/src/main/resources/com/github/heuermh/cooper/Messages.properties b/src/main/resources/com/github/heuermh/cooper/Messages.properties
index 3ae9d0d..2a208e3 100644
--- a/src/main/resources/com/github/heuermh/cooper/Messages.properties
+++ b/src/main/resources/com/github/heuermh/cooper/Messages.properties
@@ -21,6 +21,7 @@ coop.usage.descriptionHeading = %n
 
 human-readable = Format content sizes in binary multi-byte units.
 show-header = Show column header row in output.
+region = AWS region, default US_WEST_2.
 reverse-columns = Reverse the order of output columns.
-uris = Zero or more s3 URIs.
+uris = One or more s3 URIs.
 verbose = Show additional logging messages.