Iran is the greatest threat to peace in the Middle East, the commander of the US Central Command, Army General Joseph Votel, told the House Armed Services Committee on Wednesday (29 March) while discussing the ongoing campaign against Islamic State (Isis) in Iraq and Syria.

He saw security threats to the US from militant organisations and external forces like Russia and China, and called for a whole-of-government approach for maintaining a trained force in the troubled regions alongside local troops.

Votel said Iran was aiming to become "the hegemon" (or supreme leader) in the region, but had become the root of many problems for countries like Iraq, Syria, Afghanistan, Yemen, Egypt and the Sinai, and Pakistan, according to a press release.

"It is my view that Iran poses the greatest long-term threat to stability in this part of the world," he noted, adding that these conflict-hit nations were the focus of the US central command. "We are making progress in many areas, but much, much work remains."

Explaining the spread of militant groups in the conflict zones, Votel said the main contributing factors included "heightened ethno-sectarian tensions, economic uncertainty, weak or corrupt governance, civil wars, and humanitarian crisis". Extremist organisations and terrorist groups such as al-Qaeda and Isis exploit the political and economic turmoil in the countries to establish their own reign, he said.

"These groups have clearly indicated their desire and intent to attack the US homeland, our interests abroad and the interests of our partners and allies," the general said of the extended threats from the militant groups.

He urged the committee to continue its support in terms of providing resources to the soldiers in fighting extremist forces across the world.

Referring to the existing campaigns in Iraq, Syria and Afghanistan where US forces are training local soldiers in their fight against extremist forces, Votel said: "While this approach ... does present some challenges and can be more time-consuming, it is proving effective and is likely to pay significant dividends moving forward.

"The fact is we cannot surge trust in times of crisis, and we must do what is necessary now to assure our partners of our commitment and our staying power."