The $4.7 billion deal to buy US meats icon Smithfield Foods that China's Shuanghui International announced on Wednesday represents more than a smart business decision.

To meet the soaring appetite for pork and other high-quality meats in the world's most populous country, such an effort to lock in a strong supply of pork for the Chinese market is obviously long overdue.

However, as one of the largest-ever Chinese purchases of a US company, it seems likely that the deal will also be a lightening rod for the strength of US protectionism.