Where are Windows Phone 8.1 development tools

Appears that the SDK requires VS 2013.  I have been running VS 2012 with WP8 SDK to this point.

Windows Phone 8.1 development tools
https://dev.windowsphone.com/en-us/downloadsdk

8.1 Dev preview app

https://dev.windowsphone.com/en-us/develop/devpreview

Sample Apps source code

http://appstudio.windowsphone.com/Home/SampleApps