Chinese Bid for Unocal

This is one of those topics that makes me nervous. A Chinese Governmental entity Coonc Ltd. is looking to purchase Unocal. Unocal is a large US oil company.

Opposition to the Chinese firm's bid intensified in Washington as House members held a hearing and a senior Republican legislator questioned the involvement of a prominent U.S. law firm lobbying for Cnooc. The Chinese company would need approval from U.S. regulators to purchase Unocal, including the endorsement of a multi-agency panel that would decide whether the sale would pose a national security threat.

And

Anti-China sentiment in Congress has been building for several years, stemming from security concerns, complaints of currency manipulation and intellectual property theft, and other unfair trade practices. The hearing Wednesday by the House Armed Services Committee was dominated by witnesses who opposed Cnooc's bid to buy Unocal. Committee Chairman Duncan Hunter (R-Calif.), told reporters that Cnooc's proposal should be rejected on security grounds.

Most of Unocal's oil and natural gas reserves are overseas, which Hunter said is a problem for the United States because the company provides natural gas in Southeast Asia and is an investor in pipelines running through Azerbaijan, Georgia and Turkey, which he identified as "critical players and key U.S. allies in the global war on terrorism."

I do understand the security grounds that they mention. I just wonder how much of their resources are used to supply the US economy. The reason for this particular concern is the same as my arguments for economic protectionism for certain key industries that are failing in the US. (Like Steel) If a conflict occurs with China, what impact would there ownership of this company have on the economy and safety of the US? Could China manipulate the company in a manner that does damage to the economy?

I've found economic analysis of the bid, and some broader conversations.
This one discusses more on topic of what security means in this context.