diff --git a/pkg/apis/core/v1/zz_generated.validations.go b/pkg/apis/core/v1/zz_generated.validations.go
index e5aaa2b3882..c5e54847792 100644
--- a/pkg/apis/core/v1/zz_generated.validations.go
+++ b/pkg/apis/core/v1/zz_generated.validations.go
@@ -89,6 +89,11 @@ func Validate_ReplicationControllerSpec(ctx context.Context, op operation.Operat
 	// field corev1.ReplicationControllerSpec.Replicas
 	errs = append(errs,
 		func(fldPath *field.Path, obj, oldObj *int32) (errs field.ErrorList) {
+			// optional fields with default values are effectively required
+			if e := validate.RequiredPointer(ctx, op, fldPath, obj, oldObj); len(e) != 0 {
+				errs = append(errs, e...)
+				return // do not proceed
+			}
 			errs = append(errs, validate.Minimum(ctx, op, fldPath, obj, oldObj, 0)...)
 			return
 		}(fldPath.Child("replicas"), obj.Replicas, safe.Field(oldObj, func(oldObj *corev1.ReplicationControllerSpec) *int32 { return oldObj.Replicas }))...)
diff --git a/pkg/apis/core/validation/validation.go b/pkg/apis/core/validation/validation.go
index 8416ec8a074..78abddc1522 100644
--- a/pkg/apis/core/validation/validation.go
+++ b/pkg/apis/core/validation/validation.go
@@ -6322,7 +6322,7 @@ func ValidateReplicationControllerSpec(spec, oldSpec *core.ReplicationController
 	allErrs = append(allErrs, ValidateNonnegativeField(int64(spec.MinReadySeconds), fldPath.Child("minReadySeconds"))...)
 	allErrs = append(allErrs, ValidateNonEmptySelector(spec.Selector, fldPath.Child("selector"))...)
 	if spec.Replicas == nil {
-		allErrs = append(allErrs, field.Required(fldPath.Child("replicas"), ""))
+		allErrs = append(allErrs, field.Required(fldPath.Child("replicas"), "").MarkCoveredByDeclarative())
 	} else {
 		allErrs = append(allErrs, ValidateNonnegativeField(int64(*spec.Replicas), fldPath.Child("replicas")).MarkCoveredByDeclarative()...)
 	}
diff --git a/staging/src/k8s.io/api/core/v1/generated.proto b/staging/src/k8s.io/api/core/v1/generated.proto
index 30353a0bd37..4f5862d2886 100644
--- a/staging/src/k8s.io/api/core/v1/generated.proto
+++ b/staging/src/k8s.io/api/core/v1/generated.proto
@@ -5085,6 +5085,7 @@ message ReplicationControllerSpec {
   // Defaults to 1.
   // More info: https://kubernetes.io/docs/concepts/workloads/controllers/replicationcontroller#what-is-a-replicationcontroller
   // +optional
+  // +k8s:optional
   // +default=1
   // +k8s:minimum=0
   optional int32 replicas = 1;
diff --git a/staging/src/k8s.io/api/core/v1/types.go b/staging/src/k8s.io/api/core/v1/types.go
index 0da3e37f7b5..e4dc107e665 100644
--- a/staging/src/k8s.io/api/core/v1/types.go
+++ b/staging/src/k8s.io/api/core/v1/types.go
@@ -5107,6 +5107,7 @@ type ReplicationControllerSpec struct {
 	// Defaults to 1.
 	// More info: https://kubernetes.io/docs/concepts/workloads/controllers/replicationcontroller#what-is-a-replicationcontroller
 	// +optional
+	// +k8s:optional
 	// +default=1
 	// +k8s:minimum=0
 	Replicas *int32 `json:"replicas,omitempty" protobuf:"varint,1,opt,name=replicas"`