diff --git a/bumble/device.py b/bumble/device.py
index 9240fe93..6cf93cf1 100644
--- a/bumble/device.py
+++ b/bumble/device.py
@@ -6198,19 +6198,23 @@ def on_connection_request(
                 parameters=Connection.Parameters(0, 0, 0),
             )
 
-            self.host.send_command_sync(
-                hci.HCI_Accept_Connection_Request_Command(
-                    bd_addr=bd_addr,
-                    role=0x01,  # Remain the peripheral
+            utils.AsyncRunner.spawn(
+                self.host.send_async_command(
+                    hci.HCI_Accept_Connection_Request_Command(
+                        bd_addr=bd_addr,
+                        role=0x01,  # Remain the peripheral
+                    )
                 )
             )
 
         # reject incoming connection
         else:
-            self.host.send_command_sync(
-                hci.HCI_Reject_Connection_Request_Command(
-                    bd_addr=bd_addr,
-                    reason=hci.HCI_CONNECTION_REJECTED_DUE_TO_LIMITED_RESOURCES_ERROR,
+            utils.AsyncRunner.spawn(
+                self.host.send_async_command(
+                    hci.HCI_Reject_Connection_Request_Command(
+                        bd_addr=bd_addr,
+                        reason=hci.HCI_CONNECTION_REJECTED_DUE_TO_LIMITED_RESOURCES_ERROR,
+                    )
                 )
             )
 
diff --git a/bumble/l2cap.py b/bumble/l2cap.py
index 774b8a94..b4f6a983 100644
--- a/bumble/l2cap.py
+++ b/bumble/l2cap.py
@@ -2553,15 +2553,17 @@ def on_l2cap_connection_parameter_update_request(
                     result=L2CAP_CONNECTION_PARAMETERS_ACCEPTED_RESULT,
                 ),
             )
-            self.host.send_command_sync(
-                hci.HCI_LE_Connection_Update_Command(
-                    connection_handle=connection.handle,
-                    connection_interval_min=request.interval_min,
-                    connection_interval_max=request.interval_max,
-                    max_latency=request.latency,
-                    supervision_timeout=request.timeout,
-                    min_ce_length=0,
-                    max_ce_length=0,
+            utils.AsyncRunner.spawn(
+                self.host.send_async_command(
+                    hci.HCI_LE_Connection_Update_Command(
+                        connection_handle=connection.handle,
+                        connection_interval_min=request.interval_min,
+                        connection_interval_max=request.interval_max,
+                        max_latency=request.latency,
+                        supervision_timeout=request.timeout,
+                        min_ce_length=0,
+                        max_ce_length=0,
+                    )
                 )
             )
         else:
diff --git a/bumble/smp.py b/bumble/smp.py
index 3a90d523..874dcca2 100644
--- a/bumble/smp.py
+++ b/bumble/smp.py
@@ -1061,12 +1061,14 @@ def send_identity_address_command(self) -> None:
     def start_encryption(self, key: bytes) -> None:
         # We can now encrypt the connection with the short term key, so that we can
         # distribute the long term and/or other keys over an encrypted connection
-        self.manager.device.host.send_command_sync(
-            HCI_LE_Enable_Encryption_Command(
-                connection_handle=self.connection.handle,
-                random_number=bytes(8),
-                encrypted_diversifier=0,
-                long_term_key=key,
+        utils.AsyncRunner.spawn(
+            self.manager.device.host.send_async_command(
+                HCI_LE_Enable_Encryption_Command(
+                    connection_handle=self.connection.handle,
+                    random_number=bytes(8),
+                    encrypted_diversifier=0,
+                    long_term_key=key,
+                )
             )
         )