The United States will look at "other options" to increase pressure on North Korea and strengthen defense of allies if Pyongyang conducts yet another nuclear test, a State Department spokesman said Tuesday.

South Korean President Park Geun-hye said earlier Tuesday that the North has "completed preparations for a fifth nuclear test and it is in a situation in which it can carry out the test at any time. She also warned of stronger sanctions against Pyongyang.

"We're going to look at other options as we move forward if North Korea continues with this kind of behavior," State Department Deputy Spokesman Mark Toner said at a regular briefing in response to a question about possible consequences Pyongyang could face in case of a nuclear test. 

"As North Korea continues to make decisions that we believe are counterproductive, we've got to also continue to look at what our options in terms of response, and both one to ensure the security and safety of our allies and protect the security of the peninsula, but also to make every effort to convince North Korea to come back to serious discussions about its program," he said.

Toner declined to elaborate on what other options could be, saying he doesn't want to "announce anything before it's been fully formed and fully vetted." Still, he said the U.S. goal is two-fold: how to put additional pressure on the North to make it return to the negotiating table and how to ensure our allies are protected.

"We call on North Korea to refrain from actions that further destabilize the region and focus on what it needs to do, which is take concrete steps toward fulfilling its comments and its obligations to denuclearize," Toner said. 

"The United States remains steadfast in its commitment to the security of the peninsula and to its allies, the defense of its allies, and we're going to continue to coordinate with Japan, with South Korea and other allies and partners," he said.

Toner also urged China to exercise influence with the North.

White House press secretary Josh Earnest also said the U.S. will continue to ramp up the pressure on the North and continue to work closely with the Chinese government, saying Beijing has more influence with the North Korean government than any other country in the world.

"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 denuclearize the Korean Peninsula and come into compliance with their international obligations," Earnest said.

Concerns have grown bigger that Pyongyang could carry out yet another nuclear test just a few months after its fourth test in an effort to project an image of Kim Jong-un as a strong leader in the lead-up to the Workers' Party Congress next month.

Earlier in the day, the Institute for Science and International Security said in a report that activity at North Korea's nuclear test site has significantly decreased in a possible indication that the communist nation has completed all preparations for a fifth nuclear test. (Yonhap)