Navigation.PopAsync threading...

Hello, is Navigation.PopAsync() require BeginInvokeOnMainThread if being called from a separate thread? For example from a WebService ASync Completed event?

void _ws_VerifyUserCompleted(object sender, VerifyUserCompletedEventArgs e) {
  Device.BeginInvokeOnMainThread(() => DisplayAlert("This is a title", "This is a message", "Ok"));
  Navigation.PopAsync();
}

or

void _ws_VerifyUserCompleted(object sender, VerifyUserCompletedEventArgs e) {
  Device.BeginInvokeOnMainThread(() => {
    DisplayAlert("This is a title", "This is a message", "Ok"));
    Navigation.PopAsync();
  }
}