US concerned over N Korea's provocative actions

Amidst reports that North Korea is preparing for a fifth nuclear test, the US has expressed strong concern over such "provocative actions" and said it will continue to ramp up the pressure on the reclusive nation to compel it fulfil its international obligations.
"We have expressed our strong concern about those provocative actions. We have marshalled the international community to respond accordingly," White House Press Secretary Josh Earnest told reporters.
"Earlier this year, there was a response from the United Nations that actually put in place the farthest-reaching sanctions against North Korea that targeted specific elements of their economy, such as it is, that we know are used to fund these illicit activities," he said.

"So we're going to continue to ramp up the pressure on the North Korean regime," he said adding that the US is going to continue to work closely with the Chinese government that has more influence with the North Korean government than any other country in the world.
"And we're going to continue to make clear that the path that North Korea must choose to rejoin the international community is one that involves them committing to denuclearise the Korean Peninsula and come into compliance with their international obligations," he said.
Given the potential threat coming from a North Korean missile test, Earnest said the US has increased the deployment of naval assets in the Asia Pacific as a part of the Asia pivot, but that also has enhanced its ability to counter ballistic missiles in that region of the world.

Over the last several years, there's been equipment that's been deployed to places like Japan and Guam that could be effective in protecting the US and its allies from ballistic missiles.
North Korea conducted a fourth nuclear test in January and a long-range rocket launch in February, and the country was subsequently slapped with tough UN sanctions.