diff --git a/java/google/registry/tools/LockOrUnlockDomainCommand.java b/java/google/registry/tools/LockOrUnlockDomainCommand.java
index a5a2e3f65..ae03e7360 100644
--- a/java/google/registry/tools/LockOrUnlockDomainCommand.java
+++ b/java/google/registry/tools/LockOrUnlockDomainCommand.java
@@ -23,8 +23,10 @@ import static google.registry.util.CollectionUtils.findDuplicates;
 import com.beust.jcommander.Parameter;
 import com.google.common.base.Joiner;
 import com.google.common.collect.ImmutableSet;
+import google.registry.config.RegistryConfig.Config;
 import google.registry.model.eppcommon.StatusValue;
 import java.util.List;
+import javax.inject.Inject;
 
 /** Shared base class for commands to registry lock or unlock a domain via EPP. */
 public abstract class LockOrUnlockDomainCommand extends MutatingEppToolCommand {
@@ -35,14 +37,17 @@ public abstract class LockOrUnlockDomainCommand extends MutatingEppToolCommand {
 
   @Parameter(
       names = {"-c", "--client"},
-      description = "Client identifier of the registrar to execute the command as",
-      required = true
-  )
+      description =
+          "Client ID of the requesting registrar if applicable, otherwise the registry registrar")
   String clientId;
 
   @Parameter(description = "Names of the domains", required = true)
   private List<String> mainParameters;
 
+  @Inject
+  @Config("registryAdminClientId")
+  String registryAdminClientId;
+
   protected ImmutableSet<String> getDomains() {
     return ImmutableSet.copyOf(mainParameters);
   }
@@ -51,6 +56,11 @@ public abstract class LockOrUnlockDomainCommand extends MutatingEppToolCommand {
   protected void initEppToolCommand() throws Exception {
     // Superuser status is required to update registry lock statuses.
     superuser = true;
+
+    // Default clientId to the registry registrar account if otherwise unspecified.
+    if (clientId == null) {
+      clientId = registryAdminClientId;
+    }
     String duplicates = Joiner.on(", ").join(findDuplicates(mainParameters));
     checkArgument(duplicates.isEmpty(), "Duplicate domain arguments found: '%s'", duplicates);
     initMutatingEppToolCommand();
diff --git a/java/google/registry/tools/RegistryToolComponent.java b/java/google/registry/tools/RegistryToolComponent.java
index fd688c6c6..290e1af79 100644
--- a/java/google/registry/tools/RegistryToolComponent.java
+++ b/java/google/registry/tools/RegistryToolComponent.java
@@ -91,12 +91,14 @@ interface RegistryToolComponent {
   void inject(GetKeyringSecretCommand command);
   void inject(GhostrydeCommand command);
   void inject(ListCursorsCommand command);
+  void inject(LockDomainCommand command);
   void inject(LoginCommand command);
   void inject(LogoutCommand command);
   void inject(PendingEscrowCommand command);
   void inject(RenewDomainCommand command);
   void inject(SendEscrowReportToIcannCommand command);
   void inject(SetupOteCommand command);
+  void inject(UnlockDomainCommand command);
   void inject(UpdateCursorsCommand command);
   void inject(UpdateDomainCommand command);
   void inject(UpdateKmsKeyringCommand command);
diff --git a/javatests/google/registry/tools/LockDomainCommandTest.java b/javatests/google/registry/tools/LockDomainCommandTest.java
index 53c614939..39eeffc37 100644
--- a/javatests/google/registry/tools/LockDomainCommandTest.java
+++ b/javatests/google/registry/tools/LockDomainCommandTest.java
@@ -18,12 +18,14 @@ import static com.google.common.truth.Truth.assertThat;
 import static google.registry.model.eppcommon.StatusValue.SERVER_TRANSFER_PROHIBITED;
 import static google.registry.testing.DatastoreHelper.newDomainResource;
 import static google.registry.testing.DatastoreHelper.persistActiveDomain;
+import static google.registry.testing.DatastoreHelper.persistNewRegistrar;
 import static google.registry.testing.DatastoreHelper.persistResource;
 import static google.registry.testing.JUnitBackports.assertThrows;
 import static google.registry.tools.LockOrUnlockDomainCommand.REGISTRY_LOCK_STATUSES;
 
 import com.google.common.collect.ImmutableList;
 import com.google.common.collect.ImmutableMap;
+import google.registry.model.registrar.Registrar.Type;
 import java.util.ArrayList;
 import java.util.List;
 import org.junit.Before;
@@ -35,6 +37,8 @@ public class LockDomainCommandTest extends EppToolCommandTestCase<LockDomainComm
   @Before
   public void before() {
     eppVerifier.expectSuperuser();
+    persistNewRegistrar("adminreg", "Admin Registrar", Type.REAL, 693L);
+    command.registryAdminClientId = "adminreg";
   }
 
   @Test
@@ -91,6 +95,15 @@ public class LockDomainCommandTest extends EppToolCommandTestCase<LockDomainComm
     runCommandForced("--client=NewRegistrar", "example.tld");
   }
 
+  @Test
+  public void testSuccess_defaultsToAdminRegistrar_ifUnspecified() throws Exception {
+    persistActiveDomain("example.tld");
+    runCommandForced("example.tld");
+    eppVerifier
+        .expectClientId("adminreg")
+        .verifySent("domain_lock.xml", ImmutableMap.of("DOMAIN", "example.tld"));
+  }
+
   @Test
   public void testFailure_duplicateDomainsAreSpecified() throws Exception {
     IllegalArgumentException e =
diff --git a/javatests/google/registry/tools/UnlockDomainCommandTest.java b/javatests/google/registry/tools/UnlockDomainCommandTest.java
index b52a2673d..94e74669f 100644
--- a/javatests/google/registry/tools/UnlockDomainCommandTest.java
+++ b/javatests/google/registry/tools/UnlockDomainCommandTest.java
@@ -20,12 +20,14 @@ import static google.registry.model.eppcommon.StatusValue.SERVER_TRANSFER_PROHIB
 import static google.registry.model.eppcommon.StatusValue.SERVER_UPDATE_PROHIBITED;
 import static google.registry.testing.DatastoreHelper.newDomainResource;
 import static google.registry.testing.DatastoreHelper.persistActiveDomain;
+import static google.registry.testing.DatastoreHelper.persistNewRegistrar;
 import static google.registry.testing.DatastoreHelper.persistResource;
 import static google.registry.testing.JUnitBackports.assertThrows;
 
 import com.google.common.collect.ImmutableList;
 import com.google.common.collect.ImmutableMap;
 import com.google.common.collect.ImmutableSet;
+import google.registry.model.registrar.Registrar.Type;
 import java.util.ArrayList;
 import java.util.List;
 import org.junit.Before;
@@ -37,6 +39,8 @@ public class UnlockDomainCommandTest extends EppToolCommandTestCase<UnlockDomain
   @Before
   public void before() {
     eppVerifier.expectSuperuser();
+    persistNewRegistrar("adminreg", "Admin Registrar", Type.REAL, 693L);
+    command.registryAdminClientId = "adminreg";
   }
 
   private static void persistLockedDomain(String domainName) {
@@ -99,6 +103,15 @@ public class UnlockDomainCommandTest extends EppToolCommandTestCase<UnlockDomain
     runCommandForced("--client=NewRegistrar", "example.tld");
   }
 
+  @Test
+  public void testSuccess_defaultsToAdminRegistrar_ifUnspecified() throws Exception {
+    persistLockedDomain("example.tld");
+    runCommandForced("example.tld");
+    eppVerifier
+        .expectClientId("adminreg")
+        .verifySent("domain_unlock.xml", ImmutableMap.of("DOMAIN", "example.tld"));
+  }
+
   @Test
   public void testFailure_duplicateDomainsAreSpecified() throws Exception {
     IllegalArgumentException e =