A convoy of aid from the Syrian Arab Red Crescent waits on the outskirts of the besieged rebel-held Syrian town of Madaya—AFP

Defence secretary Ashton Carter on Thursday issued a stern warning to those, in particular the Islamic State (ISIS) militants, who threaten or try to harm the US.

“We’ve made it clear that those who threaten or incite harm to Americans, wherever they are, will surely come to feel the long arm and the hard fist of justice,” Mr Carter said in an address to his soldiers at Fort Campbell, Kentucky.

He said the US campaign to deliver ISIS a lasting defeat, at its source and wherever it rears its head, is far from over.

“But the outcome is not uncertain. There will be extraordinary challenges ahead, and as I will emphasize in Paris next week, we must all do more,” he said.

“But our campaign will continue to adapt and build on our success as ISIL’s territory decreases, its resources dwindle and local, capable forces gain the capacity to not only win on the field of battle, but to lay the foundation for lasting security in the region and a more secure future for the world,” he added.

Observing that US alone cannot accomplish the goal of defeating the ISIS, he said its lasting defeat must be a global undertaking because it’s a global threat.

“Any nation that cares about the safety of its people or the future of its civilisation must know this. America will continue to lead the fight, but there can be no free riders,” he said.

“That means as we invest in the acceleration of the campaign, so much every one of our coalition partners and every nation in a position to help,” he said.

“That means greater military contributions, but it also means greater diplomatic, political and economic engagement. It means development and reconstruction. It means actions at home and abroad to disrupt, dismantle and degrade ISIL’s capabilities. It means stepping up,” he said.