diff --git a/java/com/google/domain/registry/tools/CreateOrUpdateRegistrarCommand.java b/java/com/google/domain/registry/tools/CreateOrUpdateRegistrarCommand.java
index a127c8b3b..57aa161ef 100644
--- a/java/com/google/domain/registry/tools/CreateOrUpdateRegistrarCommand.java
+++ b/java/com/google/domain/registry/tools/CreateOrUpdateRegistrarCommand.java
@@ -217,6 +217,13 @@ abstract class CreateOrUpdateRegistrarCommand extends MutatingCommand {
       arity = 1)
   private Boolean blockPremiumNames;
 
+  @Nullable
+  @Parameter(
+      names = "--sync_groups",
+      description = "Whether this registrar's groups should be updated at the next scheduled sync",
+      arity = 1)
+  private Boolean contactsRequireSyncing;
+
   @Nullable
   @Parameter(
       names = "--drive_id",
@@ -361,6 +368,9 @@ abstract class CreateOrUpdateRegistrarCommand extends MutatingCommand {
       if (blockPremiumNames != null) {
         builder.setBlockPremiumNames(blockPremiumNames);
       }
+      if (contactsRequireSyncing != null) {
+        builder.setContactsRequireSyncing(contactsRequireSyncing);
+      }
       // When creating a new REAL registrar or changing the type to REAL, a passcode is required.
       // Leave existing REAL registrars alone.
       if (Registrar.Type.REAL.equals(registrarType)
diff --git a/javatests/com/google/domain/registry/tools/UpdateRegistrarCommandTest.java b/javatests/com/google/domain/registry/tools/UpdateRegistrarCommandTest.java
index 22c0a1a32..20aeb8166 100644
--- a/javatests/com/google/domain/registry/tools/UpdateRegistrarCommandTest.java
+++ b/javatests/com/google/domain/registry/tools/UpdateRegistrarCommandTest.java
@@ -17,6 +17,7 @@ package com.google.domain.registry.tools;
 import static com.google.common.base.Preconditions.checkNotNull;
 import static com.google.common.base.Strings.isNullOrEmpty;
 import static com.google.common.truth.Truth.assertThat;
+import static com.google.domain.registry.model.registrar.Registrar.loadByClientId;
 import static com.google.domain.registry.testing.CertificateSamples.SAMPLE_CERT;
 import static com.google.domain.registry.testing.CertificateSamples.SAMPLE_CERT_HASH;
 import static com.google.domain.registry.testing.DatastoreHelper.createTlds;
@@ -416,6 +417,15 @@ public class UpdateRegistrarCommandTest extends CommandTestCase<UpdateRegistrarC
         .isEqualTo("whois.goth.black");
   }
 
+  @Test
+  public void testSuccess_triggerGroupSyncing_works() throws Exception {
+    persistResource(
+        loadByClientId("NewRegistrar").asBuilder().setContactsRequireSyncing(false).build());
+    assertThat(loadByClientId("NewRegistrar").getContactsRequireSyncing()).isFalse();
+    runCommand("--sync_groups=true", "--force", "NewRegistrar");
+    assertThat(loadByClientId("NewRegistrar").getContactsRequireSyncing()).isTrue();
+  }
+
   @Test
   public void testFailure_invalidRegistrarType() throws Exception {
     thrown.expect(ParameterException.class);