The U.S. navy’s nuclear-powered supercarrier USS John C. Stennis docked at Busan Port on Sunday in the latest reinforcement of U.S. military assets aimed at deterring North Korea from provocative acts.

The carrier came to South Korea to participate in the allies’ annual joint military exercises, which this year are the largest ever, in the wake of North Korea’s recent nuclear test and long-range ballistic missile launch.

Besides the carrier, the U.S. -- in a show of force aimed at deterring the North from making further provocations -- had already sent the B-52 strategic bombers and deployed F-22 stealth fighters. There are reports that the U.S. will also bring in the B-2 stealth bombers.

The presence of such powerful U.S. military force may well unnerve the North Korean military and its young commander in chief, Kim Jong-un. The fact that the allies’ drills this year focus -- for the first time -- more on offense than defense should make them more apprehensive than ever.

The allies’ landing drills which were held successfully over the weekend have turned to inland assaults targeting key facilities in North Korea. The drills also include simulated preemptive, surgical strikes against selected targets.

From the North’s standpoint, the allies’ military moves -- coming along with the harsh international sanctions -- certainly pose the greatest threat in years to the country and the regime of Kim Jong-un who succeeded his father five years ago.

Under the circumstances, one of the first things the 33-year-old Kim and his generals will recall may be the Clinton administration’s plan to bomb the nuclear facilities in Yongbyon during the 1994 nuclear crisis, which was aborted due to opposition by South Korean President Kim Young-sam.

North Korea’s reactions clearly reflect jitters on the part of Kim and his military aides. Since the U.N. Security Council imposed the toughest-ever sanctions early this month, the North fired six rockets into the East Sea and then two ballistic missiles with a range of about 500 kilometers.

But Kim and his generals, knowing that those traditional provocations will not be able to turn the situation around, are raising the ante to the highest level with threats of nuclear attacks and war.

Kim himself showed up successively in the state propaganda apparatus to deliver the threats. His first response toward the South Korea-U.S. drills was to order the military to put North Korea’s nuclear arsenal on standby for an attack at any moment.

Then the media showed a picture of Kim and nuclear scientists standing by what it claimed was a miniaturized warhead that could be mounted on a missile. Then there was another photo of Kim visiting the launch site for ballistic missiles, where he ordered officials to conduct more nuclear tests and develop various means of delivery -- on the ground, in the air, at sea and underwater.

North Korean military authorities went on to say that they were ready to stage operations to “liberate” Seoul and the whole of South Korea. The word liberate was used by the North during the 1950-53 Korean War.

It is not rare for the North to threaten the South using expressions like turning Seoul into a sea of fire, but it is the first time in recent years that Pyongyang has threatened the possibility of war by mentioning liberation.

As experts see, the North’s acts and words reflect its fear of the allies’ military moves and the effects the U.N.-led sanctions will have on the country. The pressure should be sustained so that Kim can never think about a further provocation, let alone starting a war.