MPs will vote to decide later today whether the UK should join US-led air strikes on Islamic State in Iraq.
Action is almost certain to be approved as The Tories, Liberal Democrats and Labour all back it – and could begin within 24 hours.
The coalition government says it is legal because it was requested by the Iraqi government.
Ahead of the debate Defence Secretary Michael Fallon warned the campaign could be a “long haul” of “two to three years”.
The terrorist group IS has seized large parts of Iraq and Syria in recent months.
The UK government is not proposing any involvement in air strikes on Syria.
Today the US issued images of the aftermath of air strikes on refineries held by the Islamic group
But aiding the military effort does not have universal support.
Labour’s Diane Abbott, Jeremy Corbyn and John McDonnell are among those that have signed a letter which said bombing Iraq would “only exacerbate the situation”.
Six RAF Tornados in Cyprus have been ready to carry out air strikes for weeks. Their laser-guided bombs and missiles will be loaded and armed soon after Parliament gives the green light.
The Tornados have already been flying reconnaissance missions over Iraq and will have identified potential targets. But some of the obvious ones have already been hit by US war planes during the last month.