Why has the united states taken a keen interest in china in recent years?

Well you see this question is actually a very complicated. First of all China is going to overtake the United States as the world's largest economy in less than a decade and pushing the United States out of the Forefront of being a global leader in economy and trade. Second, China is growing its military presence in Nations around the world for example China has built its first overseas military base in Djibouti and China has constructed numerous bases in the South China Sea. Finally China is building relationships with Nations the United States has neglected to do so with for example Pakistan, Afghanistan Myanmar, Lao.

Ship building industry , good luck : )