Ahead of Chinese President Xi Jinping's US visit, President Barack Obama has said cyber- attacks emanating from China are "not acceptable" and will be treated as a "core national security threat".

"We've made very clear to the Chinese that there are certain practices that they're engaging in that we know are emanating from China and are not acceptable," Obama said at a town hall meeting with soldiers at Fort Meade.

Obama said President Xi will be coming for a state visit in a couple of weeks time. "We can choose to make this an area of competition -- which I guarantee you we'll win if we have to -- or, alternatively, we can come to an agreement in which we say, this isn't helping anybody; let's instead try to have some basic rules of the road in terms of how we operate," Obama said in response to a question.

"There's still going to be individual actors, there are going to be terrorist networks and others, so we're still going to have to build a strong defence. But one of our first and most important efforts has to be to get the states that may be sponsoring cyber-attacks to understand that there comes a point at which we consider this a core national security threat and we will treat it as such," he said.