Toshiba's CEO had good reason to sound a trifle defensive about his company's $5.4 billion purchase of U.S.-based nuclear power company Westinghouse.

After all, almost every other high-profile Japanese corporate buyout in the U.S. has turned out badly.

"I'd like to make this the first success story," CEO Atsutoshi Nishida said following the announcement earlier this month that the electronics company will buy Westinghouse Electric Co. from British Nuclear Fuels PLC.

The move signals the determination of Toshiba, already a leading builder of nuclear power plants, to make nuclear energy a pillar of its business, along with computer chips and electronics. Toshiba has built 22 nuclear power plants in Japan since entering the business in 1966, and is building another in Japan and two in Taiwan.

By acquiring Westinghouse, Toshiba becomes the world's No. 1 nuclear power plant company, with a 28 percent share of the global market, Nishida said.

With soaring oil prices, experts say nuclear energy is becoming a more attractive option in the U.S. and elsewhere, despite safety concerns.

In particular, the company is betting China's nuclear power market will balloon. Toshiba has not built a nuclear plant in China so far, but it has operations in 63 locations there, including sales outlets, distribution centers and production plants, employing 20,000 people.

Still, there are numerous question marks about the deal.

For one, many believe Toshiba overpaid for Westinghouse. The expected price had been about half what was finally agreed to. British Nuclear Fuels paid $1 billion when it bought Westinghouse in 1999.

"It was a far too expensive purchase," said Kota Ezawa, an analyst at Daiwa Institute of Research in Tokyo. "Nuclear energy is a profitable business, but even considering that, it wasn't a good deal."

Toshiba shares slipped on the deal, but have recovered on news the company is boosting investment in flash-memory computer chips. Its stock has recently traded around 670 yen per share.

Standard & Poor's and Moody's Investors Service placed Toshiba under review for a possible downgrade, warning that it had paid too much for Westinghouse and that the deal may endanger its financial position.

Toshiba maintains it will recoup its investment in 15 or 20 years. It plans to retain at least a 51 percent stake in Monroeville, Pa.-based Westinghouse, and it is in talks with several companies seeking minority shareholders.

Yuichi Ishida, an analyst at Mizuho Investors Securities in Tokyo, believes it is hard for investors to assess a deal that will take so long to produce profits, and questions the wisdom of channeling profits from its booming flash-memory chip business into nuclear energy.

"Toshiba is investing the money it has earned from a highly profitable business and investing it in nuclear power, which is far more questionable in profitability," Ishida said.

And the deal could fail to win regulatory approval.

As an acquisition by a Japanese company, the buyout requires approval from the Committee on Foreign Investments in the U.S., a panel within the U.S. Treasury Department that scrutinizes such deals.

The Japanese press is speculating the U.S. government would have preferred to see Westinghouse go to General Electric Co., which bid unsuccessfully against Toshiba.

Toshiba says the deal is expected to be finalized by fall. Nishida expressed confidence about getting approval from Washington, saying nuclear plants don't involve sensitive defense technology.

But there's plenty of skepticism because such issues tend to be political.

"Nuclear energy involves national policy, and it's not going to be as simple as selling other products," said Yoshihide Otake, an analyst with Shinko Securities Co. "Toshiba certainly has many hurdles left to clear."

In 1988, the U.S. banned government purchases of Toshiba products and slapped an embargo on products from a Toshiba subsidiary for selling submarine-silencing equipment to the former Soviet Union in violation of an international export control agreement designed to keep high-tech equipment with military uses out of communist hands.

The major business daily Nihon Keizai Shimbun pointed to GE's lobbying power as a defense contractor and as an important energy, financial and media group.

"It is possible the U.S. government may not approve the deal," the newspaper said in a recent commentary. "The presence of GE, which has deep ties with the U.S. government, cannot be ignored."

Toshiba has a partnership with General Electric on some nuclear plants, although it is unclear whether the partnership will continue after the Westinghouse purchase.

Adding to concerns over the Toshiba acquisition is the poor record of Japanese companies' investment forays into the U.S. -- especially for a big name like Westinghouse, associated for more than a century with home appliances, the media and energy. The firm now operates as a nuclear power plant company.

Some fear the venture may prove as disastrous as Sony Corp.'s buyout of Columbia Pictures or Mitsubishi Estate Co.'s snapping up Rockefeller Center -- both in 1989 at the height of the bubble economy.

A more recent blunder was NTT DoCoMo's investment in AT&T Wireless, announced in 2000, which merely racked up losses for the mobile carrier. NTT DoCoMo sold its 16 percent stake to Cingular Wireless in 2004.

"It's hard to say how Americans will see Japanese ownership of Westinghouse," said analyst Ishida, "It's a name that is said to be close to American people's hearts."

Toshiba has said it will leave Westinghouse operations, including management and employees, untouched.

Nishida exuded confidence, saying that he understood the way to Americans' hearts in a conference call with Westinghouse.

"I didn't forget to congratulate them for the Pittsburgh Steelers' victory in the Super Bowl," he said.