The Government should set out a "realistic vision" of the circumstances which would force the UK to join military intervention abroad, a committee of MPs have recommended.
The cross-party Defence Select Committee called on the Coalition to set clear parameters for the kind of behaviour which would force them to send troops abroad.
MPs also called on David Cameron's Government to clearly define the UK's place in the world.
Committee members warned the implications of not joining some crisis were just as profound as sending troops abroad.
The MPs suggested Russia may have felt empowered to intervene in Ukraine because the UK and other countries had failed to act in Georgia or Syria.
More top news
It'll become increasing cloudy tonight, with outbreaks of rain in the northwest
Six months on from the referendum, Political Editor Robert Peston takes a road trip to find out what people feel about Brexit now.
Donald Trump has been criticised for appointing a man who once sued the Environmental Protection Agency to be its new boss.