The next instalment in a series of "programmes" from the mlitant group Islamic State (IS) featuring British hostage John Cantlie was released today.

The video, which follows a clip of Cantlie released on Thursday, was posted shortly after the United States announced it had launched the first air strikes on IS in Syria.

Entitled 'Lend me your ears – and Messages From The British Detainee John Cantlie: Episode 1', it is similar in style to the last Cantlie video, mimicking a news report or lecture.

In the video which is almost six minutes long, the journalist and photographer describes the American response to IS as "Gulf War III".

"Not since Vietnam have we witnessed such a potential mess in the making," Cantlie says.

In last week's video, Cantlie said there would be a series of videos posted, in which he would offer an alternative explanation for his captors' actions to the one being given by Western states.

Cantlie says in the latest video that Western nations have under estimated the power and growth of IS. "Current estimates of 15,000 troops needed to fight the Islamic State are laughably low. The State has more mujahideen than this," he says.

"And this is not some undisciplined outfit with a few Kalashnikovs," he adds.

There are thought to be as many as 31,000 IS fighters in Iraq and Syria, where they are trying to create a caliphate.

The video appears to have been recorded before the American strikes on Syria began, possibly at the same time the previous clip was filmed.

Cantlie says, as before, that he has been abandoned by his own government, and describes himself as "a long-term prisoner of the Islamic State."

He was first kidnapped by IS in Syria in July 2012. He escaped with the help of the Free Syrian Army but was detained again at the end of 2012, and has been held hostage for the past 22 months.