The Netherlands, Great Britain, Estonia, Latvia, Lithuania, Norway and Denmark have created a multilateral force of at least 10.000 soldiers, with ground-, air- and marinetroups, as a reaction to Russia's aggresive behaviour in Ukraine.
The troups will be practicing together and should be deployable at short notice.
Other countries could possibly join as Prime Minister Cameron is set to announce the plans at the next NATO summit, on the 4th and 5th of September in Wales.
http://www.nu.nl/binnenland/3864983/...d-rusland.html
(I translated the important parts since it's in Dutch. The main srouce is The Financial Times, but I can't access that)