diff --git a/framework/api/system-current.txt b/framework/api/system-current.txt
index d1d51da..cfab872 100644
--- a/framework/api/system-current.txt
+++ b/framework/api/system-current.txt
@@ -279,6 +279,7 @@
     method @Nullable public String getSsid();
     method @NonNull public java.util.Set<java.lang.Integer> getSubscriptionIds();
     method @NonNull public int[] getTransportTypes();
+    method @Nullable public java.util.List<android.net.Network> getUnderlyingNetworks();
     method public boolean isPrivateDnsBroken();
     method public boolean satisfiedByNetworkCapabilities(@Nullable android.net.NetworkCapabilities);
     field public static final int NET_CAPABILITY_BIP = 31; // 0x1f
@@ -309,6 +310,7 @@
     method @NonNull @RequiresPermission(android.Manifest.permission.NETWORK_FACTORY) public android.net.NetworkCapabilities.Builder setSsid(@Nullable String);
     method @NonNull public android.net.NetworkCapabilities.Builder setSubscriptionIds(@NonNull java.util.Set<java.lang.Integer>);
     method @NonNull public android.net.NetworkCapabilities.Builder setTransportInfo(@Nullable android.net.TransportInfo);
+    method @NonNull public android.net.NetworkCapabilities.Builder setUnderlyingNetworks(@Nullable java.util.List<android.net.Network>);
     method @NonNull public static android.net.NetworkCapabilities.Builder withoutDefaultCapabilities();
   }
 
diff --git a/framework/src/android/net/NetworkCapabilities.java b/framework/src/android/net/NetworkCapabilities.java
index ae5cfda..e9bcd95 100644
--- a/framework/src/android/net/NetworkCapabilities.java
+++ b/framework/src/android/net/NetworkCapabilities.java
@@ -42,7 +42,10 @@
 
 import java.lang.annotation.Retention;
 import java.lang.annotation.RetentionPolicy;
+import java.util.ArrayList;
 import java.util.Arrays;
+import java.util.Collections;
+import java.util.List;
 import java.util.Objects;
 import java.util.Set;
 import java.util.StringJoiner;
@@ -129,6 +132,11 @@
     // Set to true when private DNS is broken.
     private boolean mPrivateDnsBroken;
 
+    // Underlying networks, if any. VPNs and VCNs typically have underlying networks.
+    // This is an unmodifiable list and it will be returned as is in the getter.
+    @Nullable
+    private List<Network> mUnderlyingNetworks;
+
     /**
      * Uid of the app making the request.
      */
@@ -184,6 +192,7 @@
         mRequestorUid = Process.INVALID_UID;
         mRequestorPackageName = null;
         mSubIds = new ArraySet<>();
+        mUnderlyingNetworks = null;
     }
 
     /**
@@ -213,6 +222,9 @@
         mRequestorUid = nc.mRequestorUid;
         mRequestorPackageName = nc.mRequestorPackageName;
         mSubIds = new ArraySet<>(nc.mSubIds);
+        // mUnderlyingNetworks is an unmodifiable list if non-null, so a defensive copy is not
+        // necessary.
+        mUnderlyingNetworks = nc.mUnderlyingNetworks;
     }
 
     /**
@@ -699,6 +711,41 @@
     }
 
     /**
+     * Set the underlying networks of this network.
+     *
+     * @param networks The underlying networks of this network.
+     *
+     * @hide
+     */
+    public void setUnderlyingNetworks(@Nullable List<Network> networks) {
+        mUnderlyingNetworks =
+                (networks == null) ? null : Collections.unmodifiableList(new ArrayList<>(networks));
+    }
+
+    /**
+     * Get the underlying networks of this network. If the caller is not system privileged, this is
+     * always redacted to null and it will be never useful to the caller.
+     *
+     * @return <li>If the list is null, this network hasn't declared underlying networks.</li>
+     *         <li>If the list is empty, this network has declared that it has no underlying
+     *         networks or it doesn't run on any of the available networks.</li>
+     *         <li>The list can contain multiple underlying networks, e.g. a VPN running over
+     *         multiple networks at the same time.</li>
+     *
+     * @hide
+     */
+    @SuppressLint("NullableCollection")
+    @Nullable
+    @SystemApi
+    public List<Network> getUnderlyingNetworks() {
+        return mUnderlyingNetworks;
+    }
+
+    private boolean equalsUnderlyingNetworks(@NonNull NetworkCapabilities nc) {
+        return Objects.equals(getUnderlyingNetworks(), nc.getUnderlyingNetworks());
+    }
+
+    /**
      * Tests for the presence of a capability on this instance.
      *
      * @param capability the capabilities to be tested for.
@@ -1901,7 +1948,8 @@
                 && equalsPrivateDnsBroken(that)
                 && equalsRequestor(that)
                 && equalsAdministratorUids(that)
-                && equalsSubscriptionIds(that);
+                && equalsSubscriptionIds(that)
+                && equalsUnderlyingNetworks(that);
     }
 
     @Override
@@ -1924,7 +1972,8 @@
                 + Objects.hashCode(mRequestorUid) * 53
                 + Objects.hashCode(mRequestorPackageName) * 59
                 + Arrays.hashCode(mAdministratorUids) * 61
-                + Objects.hashCode(mSubIds) * 67;
+                + Objects.hashCode(mSubIds) * 67
+                + Objects.hashCode(mUnderlyingNetworks) * 71;
     }
 
     @Override
@@ -1959,6 +2008,7 @@
         dest.writeInt(mRequestorUid);
         dest.writeString(mRequestorPackageName);
         dest.writeIntArray(CollectionUtils.toIntArray(mSubIds));
+        dest.writeTypedList(mUnderlyingNetworks);
     }
 
     public static final @android.annotation.NonNull Creator<NetworkCapabilities> CREATOR =
@@ -1987,6 +2037,7 @@
                 for (int i = 0; i < subIdInts.length; i++) {
                     netCap.mSubIds.add(subIdInts[i]);
                 }
+                netCap.setUnderlyingNetworks(in.createTypedArrayList(Network.CREATOR));
                 return netCap;
             }
             @Override
@@ -2078,6 +2129,16 @@
             sb.append(" SubscriptionIds: ").append(mSubIds);
         }
 
+        if (mUnderlyingNetworks != null && mUnderlyingNetworks.size() > 0) {
+            sb.append(" Underlying networks: [");
+            final StringJoiner joiner = new StringJoiner(",");
+            for (int i = 0; i < mUnderlyingNetworks.size(); i++) {
+                joiner.add(mUnderlyingNetworks.get(i).toString());
+            }
+            sb.append(joiner.toString());
+            sb.append("]");
+        }
+
         sb.append("]");
         return sb.toString();
     }
@@ -2796,6 +2857,17 @@
         }
 
         /**
+         * Set the underlying networks of this network.
+         *
+         * @param networks The underlying networks of this network.
+         */
+        @NonNull
+        public Builder setUnderlyingNetworks(@Nullable List<Network> networks) {
+            mCaps.setUnderlyingNetworks(networks);
+            return this;
+        }
+
+        /**
          * Builds the instance of the capabilities.
          *
          * @return the built instance of NetworkCapabilities.
diff --git a/tests/common/java/android/net/NetworkCapabilitiesTest.java b/tests/common/java/android/net/NetworkCapabilitiesTest.java
index 502b4f6..a619d6b 100644
--- a/tests/common/java/android/net/NetworkCapabilitiesTest.java
+++ b/tests/common/java/android/net/NetworkCapabilitiesTest.java
@@ -50,6 +50,7 @@
 
 import static com.android.modules.utils.build.SdkLevel.isAtLeastR;
 import static com.android.modules.utils.build.SdkLevel.isAtLeastS;
+import static com.android.modules.utils.build.SdkLevel.isAtLeastT;
 import static com.android.testutils.MiscAsserts.assertEmpty;
 import static com.android.testutils.MiscAsserts.assertThrows;
 import static com.android.testutils.ParcelUtils.assertParcelSane;
@@ -84,7 +85,9 @@
 import org.junit.runner.RunWith;
 import org.mockito.Mockito;
 
+import java.util.ArrayList;
 import java.util.Arrays;
+import java.util.List;
 import java.util.Set;
 
 @RunWith(AndroidJUnit4.class)
@@ -342,7 +345,9 @@
     }
 
     private void testParcelSane(NetworkCapabilities cap) {
-        if (isAtLeastS()) {
+        if (isAtLeastT()) {
+            assertParcelSane(cap, 17);
+        } else if (isAtLeastS()) {
             assertParcelSane(cap, 16);
         } else if (isAtLeastR()) {
             assertParcelSane(cap, 15);
@@ -712,6 +717,47 @@
     }
 
     @Test
+    public void testUnderlyingNetworks() {
+        assumeTrue(isAtLeastT());
+        final NetworkCapabilities nc = new NetworkCapabilities();
+        final Network network1 = new Network(100);
+        final Network network2 = new Network(101);
+        final ArrayList<Network> inputNetworks = new ArrayList<>();
+        inputNetworks.add(network1);
+        inputNetworks.add(network2);
+        nc.setUnderlyingNetworks(inputNetworks);
+        final ArrayList<Network> outputNetworks = new ArrayList<>(nc.getUnderlyingNetworks());
+        assertEquals(network1, outputNetworks.get(0));
+        assertEquals(network2, outputNetworks.get(1));
+        nc.setUnderlyingNetworks(null);
+        assertNull(nc.getUnderlyingNetworks());
+    }
+
+    @Test
+    public void testEqualsForUnderlyingNetworks() {
+        assumeTrue(isAtLeastT());
+        final NetworkCapabilities nc1 = new NetworkCapabilities();
+        final NetworkCapabilities nc2 = new NetworkCapabilities();
+        assertEquals(nc1, nc2);
+        final Network network = new Network(100);
+        final ArrayList<Network> inputNetworks = new ArrayList<>();
+        final ArrayList<Network> emptyList = new ArrayList<>();
+        inputNetworks.add(network);
+        nc1.setUnderlyingNetworks(inputNetworks);
+        assertNotEquals(nc1, nc2);
+        nc2.setUnderlyingNetworks(inputNetworks);
+        assertEquals(nc1, nc2);
+        nc1.setUnderlyingNetworks(emptyList);
+        assertNotEquals(nc1, nc2);
+        nc2.setUnderlyingNetworks(emptyList);
+        assertEquals(nc1, nc2);
+        nc1.setUnderlyingNetworks(null);
+        assertNotEquals(nc1, nc2);
+        nc2.setUnderlyingNetworks(null);
+        assertEquals(nc1, nc2);
+    }
+
+    @Test
     public void testSetNetworkSpecifierOnMultiTransportNc() {
         // Sequence 1: Transport + Transport + NetworkSpecifier
         NetworkCapabilities nc1 = new NetworkCapabilities();
@@ -1109,7 +1155,7 @@
         final TransportInfo transportInfo = new TransportInfo() {};
         final String ssid = "TEST_SSID";
         final String packageName = "com.google.test.networkcapabilities";
-        final NetworkCapabilities nc = new NetworkCapabilities.Builder()
+        final NetworkCapabilities.Builder capBuilder = new NetworkCapabilities.Builder()
                 .addTransportType(TRANSPORT_WIFI)
                 .addTransportType(TRANSPORT_CELLULAR)
                 .removeTransportType(TRANSPORT_CELLULAR)
@@ -1125,8 +1171,14 @@
                 .setSignalStrength(signalStrength)
                 .setSsid(ssid)
                 .setRequestorUid(requestUid)
-                .setRequestorPackageName(packageName)
-                .build();
+                .setRequestorPackageName(packageName);
+        final Network network1 = new Network(100);
+        final Network network2 = new Network(101);
+        final List<Network> inputNetworks = List.of(network1, network2);
+        if (isAtLeastT()) {
+            capBuilder.setUnderlyingNetworks(inputNetworks);
+        }
+        final NetworkCapabilities nc = capBuilder.build();
         assertEquals(1, nc.getTransportTypes().length);
         assertEquals(TRANSPORT_WIFI, nc.getTransportTypes()[0]);
         assertTrue(nc.hasCapability(NET_CAPABILITY_EIMS));
@@ -1144,6 +1196,11 @@
         assertEquals(ssid, nc.getSsid());
         assertEquals(requestUid, nc.getRequestorUid());
         assertEquals(packageName, nc.getRequestorPackageName());
+        if (isAtLeastT()) {
+            final List<Network> outputNetworks = nc.getUnderlyingNetworks();
+            assertEquals(network1, outputNetworks.get(0));
+            assertEquals(network2, outputNetworks.get(1));
+        }
         // Cannot assign null into NetworkCapabilities.Builder
         try {
             final NetworkCapabilities.Builder builder = new NetworkCapabilities.Builder(null);