A North Korea defence expert told the South China Morning Post it is because the country fears a radical opposition which it can not control. It so far has carried out five nuclear tests.
The United States has called on China to do more to rein in Pyongyang and Trump lavished praise on Chinese President Xi Jinping for his efforts, calling him "a good man".
Harris also says he doubts the North Korean people will rise up to topple North Korean leader Kim Jong Un.
The North did not fire any missiles or conduct a sixth nuclear test that day, but held a large-scale live-fire drill off its east coast in Wonsan, Kangwon Province.
"Meanwhile, the USA "remains open to negotiations" to achieve denuclearization of the Korean Peninsula, but warns, "we remain prepared to defend ourselves and our allies".
There is also a possibility that North Korea, facing potential changes in regional dynamics as Washington presses Beijing to pressure North Korea more aggressively, opts to mark the anniversary with a missile launch of lesser magnitude.
US trade deficit narrows in March
Imports were up for a fourth consecutive month, increasing 1.7 percent to Can$47.1 billion in March. Imports fell in March because of reduced spending on civilian aircraft, computers, oil and cars.
Admiral Harry Harris, the top USA commander in the Pacific, said on Wednesday the carrier was in the Philippine Sea, within two hours' striking distance of North Korea if needs be.
South Korea, Japan and the United States plan to ban North Korea's right to sell or trade fishing rights in its territorial waters under new sanctions to be imposed if the rogue state conducts another nuclear test. Meanwhile, the USS Carl Vinson naval strike group is making its way to the divided peninsula.
In a statement released late Friday, North Korea's Foreign Ministry accused Trump of driving the region into an "extremely unsafe phase" with the dispatch of the aircraft carrier and said the North was ready to stand up against any threat posed by the United States.
North Korea's UN Mission says the government will react to "a total war" with the United States with a nuclear war.
Matching the flurry of diplomatic and military activity in Asia, the State Department in Washington said on Monday U.S. Secretary of State Rex Tillerson would chair a special ministerial meeting of the U.N. Security Council on North Korea on Friday.
Under Kim's leadership, North Korea has been aggressively pursuing a decades-long goal of putting a nuclear warhead on an ICBM capable of reaching the USA mainland.
However, Australian defence industry minister Christopher Pyne insists that North Korea does not have a ballistic missile with a nuclear warhead capable to reaching Australia. It also launched a long-range rocket a year ago that delivered a satellite into orbit, which Washington, Seoul and others saw as a banned test of missile technology.