US troops have entered the demilitarised zone on the Iraqi border with Kuwait, according to reports.
This comes as planes in the gulf get ready to attack Iraq. One RAF Tornado has been armed with what is believed to be a cruise missile.
Sky News defence expert Francis Tusa said the weapon, slung below the belly of the plane, was a Stormshadow.
The Stormshadow is the RAF's air-launched cruise missile, as opposed to missiles like the Tomahawk which are usually fired from land or sea.
Tusa said the missile fitted to the Tornado was live, not a practice weapon.
He said live weapons were only loaded onto aircraft hours before they were expected to be used.
He said the Stormshadow was more proof that war will break out soon.
He said live weapons were only loaded onto aircraft hours before they were expected to be used.