But China is not the first foreign country to seek American energy assets.

"But my biggest concern is the preservation of Unocal's energy assets in friendly hands," he said.

"Do we want a foreign power, whose military intentions in the long term are not clear, to own energy assets inside our border?"

Last year, the company sold about $4 billion in energy assets.

Many experts question whether China even needs to own more such energy assets.

There are 18 renewable energy assets located in nine states across the US.

But China is not the first foreign country to seek energy assets owned by Americans.

Brazil says its constitution forbids the private ownership of energy assets.

The company has said it is interested in acquiring energy assets.

Within the industry, more than $10 billion worth of energy assets are for sale.