The United States isn't necessarily "afraid" of North Korea.
North Korea considers itself to still technically be at war with the US even though the Korean War ended 60 years ago. North Korea still has a massive military (their army is one of the largest in the world), and has access to nuclear weapons. Additionally, they are closely aligned with China, a country rivaling the US in sheer military and economic power. However, North Korea has no way of really directly attacking the US on their own; they only have a small navy, and their air force is no significant threat to the US's massive air forces. Rocket tests have shown that North Korea is probably not capable of hitting the US mainland with nuclear or chemical weapons.
North Korea is, however, a threat to South Korea and Japan, who are close allies of the US; since the Korean War ended, North Korea has made it clear that it intends to conquer South Korea someday. Hatred of the South and the US is one of the ways the North's government keeps their people under control- they focus hatred towards those countries, so the people forget that their life in the North isn't actually very good. In keeping with this theme, the North often threatens to attack the South, Japan or the US and sometimes does actually attack the South (for example, in November 2010 they launched an artillery strike against a small island off the coast of South Korea and killed/wounded a few people).
So it's not so much that US is "afraid" of North Korea, it's that North Korea is sometimes erratic, often throwing out threats of extreme violence for the smallest reason- or no reason at all.
Answer 2The United States has concerns against North Korea mainly for two reasons:Umm were not. North Korea can't do crap to anyone. Where did you hear of fear for them?
No. The US leads the world in enforcing sanctions against North Korea.
North Korea attacked South Korea.
No North Korea is a humanitarian nightmare.
Yes North Korea does not like the US mainly because of the country's involvement in the Korean War between North and South Korea.
to give stupid people something to be afraid of.
Yes the US is known as the American Empire to North Korea.
The US is not permitted to patrol North Korea, nor do they. The US military does however have military bases in south Korea as part of a treaty to protect them against a possible attack by North Korea.
The US was part of a United Nations force fighting North Korea and its allies.
us is bettter:)
When North Korea asked for help from China, South Korea asked for the US's help, so they broke down the bridge between China and North Korea and sent reinforcements to South Korea
The US never declared war on North Korea. The Korean War was between the United Nations and North Korea, (assisted by Russia and China).