Dual Mode Seeker Brimstone missiles fitted to a Royal Air Force Tornado GR4 aircraft
The RAF has used Brimstone missiles on Islamic State targets in Syria for the first time, Downing Street has confirmed.
Defence Secretary Michael Fallon said the United Kingdom is "playing a key role" in the fight against IS.
"A lot was made of this Brimstone missile in the lead up to the vote on Syria because the Government said this was an extra dimension in the war against Islamic State", said Sky News defence correspondent Alistair Bunkall.
What is the Brimstone missile?
Brimstone is an air-launched ground attack missile developed by MBDA for Britain's Royal Air Force. Three Brimstones are carried on a launcher that occupies a single weapon station, allowing a single aircraft to carry many missiles
Britain says its Brimstone missiles, which are created to hit fast-moving targets and have already been used by Britain's Tornado jets in Afghanistan, Libya and Iraq, should bolster the fight against IS by delivering so-called surgical strikes that minimise civilian casualties.
The UK and Saudi Arabia are the only two countries to have purchased Brimstones, and while laying out his case for British action against IS in Syria, David Cameron argued that their use would make a "meaningful difference" to the battle.
Two Tornados used Paveway bombs to strike militants attempting to mount attacks against Iraqi ground forces near the town of Haditha in western Iraq on January 6.
The attack came hours after the RAF dropped four Pave way missiles on a tunnel complex, also near Raqqa, and a Reaper drone used a Hellfire missile against a terrorist stronghold in the same area.
After details of the Syrian raids were revealed Mr Cameron's spokeswoman said: "This is part of the ongoing operation and work we are doing with coalition partners to defeat Daesh in Iraq and Syria".
RAF activity has been focused more on Iraq rather than Syria.