Last week, top foreign policy and security aides to Donald Trump gave some clues as to how the incoming US administration perceives the nuclear and missile threat from North Korea and how it is going to tackle it.

In summary, the aides who testified at their respective confirmation hearings were united in seeing North Korea as one of the “grave” threats to the US and the world. The nominees also hinted at active US engagement, including putting more pressure on China, the North’s largest benefactor and sole remaining ally. They also did not rule out the possibility of the use of force.

This means the “strategic patience” often identified with inaction will be gone with the exit of US President Barack Obama and South Korea should brace itself for a whole new security environment in this region.

The testimonies made by the nominees -- Rex Tillerson for the State Department, James Mattis for the Pentagon and Mike Pompeo for the Central Intelligence Agency -- offered a clear demonstration of how seriously they take the threat from North Korea.

Mattis said the situation on the Korean Peninsula remained volatile. He pointed to the “expansion of the North’s nuclear weapons program, continued development of increasingly sophisticated ballistic missile capabilities, and repeated threats to the US and its allies in the region.”

Pompeo also noted that the North has “dangerously accelerated” its nuclear and ballistic missile capabilities, increasing the threat it poses.

The nominee for US intelligence chief also expressed concern about the North’s cyber capabilities, pinpointing it as one of the countries that has overcome low technological standards to engage in offensive cyber operations.

So how should the US deal with threats from North Korea?

In light of what the nominees said at the hearings, one thing certain is that the Trump administration will try to toughen the current UN-led international sanctions against Pyongyang.

Tillerson made it clear that the insufficient enforcement of sanctions is the main problem in dealing with the North.

“I think a lot of our troubles today are that we do not enforce,” he said.

The nominee was as critical of China as Trump, who previously said China was doing little to pressure North Korea. Tillerson said adversaries such as Iran and North Korea pose grave threats to the world, but China “has not been a reliable partner in using its full influence to curb” the North.

He indicated that the Trump administration may impose “secondary sanctions” on Chinese firms doing business with the North. “If China is not going to comply with those UN sanctions, then it’s appropriate for the United States to consider actions to compel them to comply,” he said.

Mattis, a well-known hard-liner, said that the US should “do something” about the North’s nuclear and missile development. He indicated the US would not refrain from taking military action, adding that the US should not take anything off the table.

The nominee’s comment followed recent news reports about the possibility of the Trump administration using force to thwart the North’s nuclear and missile ambitions, including the interception of ballistic missiles and preventive or pre-emptive strikes against key facilities in the North.

Now we have a picture of the Trump administration’s North Korea policy in its early stage: It will toughen sanctions on Pyongyang and pressure China to close any loopholes in sanctions. If that does not work, the US could resort to secondary boycotts or strong-arm tactics.

It is obvious the incoming US administration will harden its position toward North Korea and China, which would raise tension in the region.

A bigger cause for concern is that the challenge could not have come at a worse time for South Korea, which is adrift, with its leader incapacitated.