diff --git a/openmp/libomptarget/src/interface.cpp b/openmp/libomptarget/src/interface.cpp
--- a/openmp/libomptarget/src/interface.cpp
+++ b/openmp/libomptarget/src/interface.cpp
@@ -21,6 +21,18 @@
 #include <cstdlib>
 #include <mutex>
 
+/// return flags of __tgt_target_XXX public APIs
+enum __tgt_target_return_t : int {
+  /// successful offload executed on a target device
+  OMP_TGT_SUCCESS = 0,
+  /// offload may not execute on the requested target device
+  /// this scenario can be caused by the device not available or unsupported
+  /// as described in the Execution Model in the specifcation
+  /// this status may not be used for target device execution failure
+  /// which should be handled internally in libomptarget
+  OMP_TGT_FAIL = ~0
+};
+
 ////////////////////////////////////////////////////////////////////////////////
 /// adds requires flags
 EXTERN void __tgt_register_requires(int64_t flags) {
@@ -284,7 +296,7 @@
      DPxPTR(host_ptr), device_id);
   if (checkDeviceAndCtors(device_id, loc)) {
     DP("Not offloading to device %" PRId64 "\n", device_id);
-    return OFFLOAD_FAIL;
+    return OMP_TGT_FAIL;
   }
 
   if (getInfoLevel() & OMP_INFOTYPE_KERNEL_ARGS)
@@ -307,7 +319,8 @@
   if (rc == OFFLOAD_SUCCESS)
     rc = AsyncInfo.synchronize();
   handleTargetOutcome(rc == OFFLOAD_SUCCESS, loc);
-  return rc;
+  assert(rc == OFFLOAD_SUCCESS && "__tgt_target_mapper unexpected failure!");
+  return OMP_TGT_SUCCESS;
 }
 
 EXTERN int __tgt_target_nowait_mapper(
@@ -357,7 +370,7 @@
      DPxPTR(host_ptr), device_id);
   if (checkDeviceAndCtors(device_id, loc)) {
     DP("Not offloading to device %" PRId64 "\n", device_id);
-    return OFFLOAD_FAIL;
+    return OMP_TGT_FAIL;
   }
 
   if (getInfoLevel() & OMP_INFOTYPE_KERNEL_ARGS)
@@ -380,7 +393,9 @@
   if (rc == OFFLOAD_SUCCESS)
     rc = AsyncInfo.synchronize();
   handleTargetOutcome(rc == OFFLOAD_SUCCESS, loc);
-  return rc;
+  assert(rc == OFFLOAD_SUCCESS &&
+         "__tgt_target_teams_mapper unexpected failure!");
+  return OMP_TGT_SUCCESS;
 }
 
 EXTERN int __tgt_target_teams_nowait_mapper(