TAIPEI, TAIWAN -- People used to scoff at tiny Taiwan's claims that it someday would retake the communist-held mainland of China. But businessmen on the island now are preparing an economic assault on the mainland that is no joke.

If they succeed, the Taiwanese businesses will bring another economic boom to this already prosperous island and in the process help modernize China. Some optimistic Taiwanese envision a combination of increasingly sophisticated Taiwanese technology and cheap mainland labor that could turn the 21st century into "the Chinese Century."

But even short of that vision, the thinking about mainland trade that is stirring Taiwan at the moment is astonishing.

Just a few years ago, it would have been hard to believe that businessmen from staunchly anticommunist Taiwan would talk openly about investing on the mainland, but they are doing it now. Even a few liberal members of the ruling Kuomintang, or nationalist party, are talking this way.

Jaw Shau-Kong, a Kuomintang legislator, argues that if Taiwan can improve the lives of people on the mainland through trade, it will help to protect Taiwan against a communist attack or takeover.

"We should go on the economic attack and influence the mainland," said Jaw, a former businessman who once worked for an American firm.

Not long ago such a view would have been considered naive, and possibly treasonous. But Jaw presented his views in the presence of a high-ranking Kuomintang official, who voiced no dissent. Officials appear to have become used to such comments.

The Kuomintang authorities seem to have gained the confidence needed to allow people to speak out more openly, even when it comes to an issue as sensitive as dealing with the mainland. This openness could eventually lead to major economic ties between Taiwan and China.

For quite some time, many Taiwanese businessmen have worked through Hong Kong companies to trade with the mainland. The Taiwanese government allows such indirect trade, but so far has banned direct trade, arguing that it would be dangerous for Taiwan to become dependent on business with the mainland.

China, on the other hand, has been consistently open to all forms of trade with Taiwan.

A National Taiwan University analyst estimates that two-way trade between Taiwan and China passing through Hong Kong has more than doubled this year, reaching a value of more than $2 billion. The mainland's official China Daily newspaper agreed in a recent report that the increase has been dramatic.

China Daily said that most of the estimated $1 billion in trade between Taiwan and the mainland last year consisted of Taiwanese exports, including industrial and electronic products and building materials. China sells medicinal herbs, food and raw materials to Taiwan.

But Taiwanese government officials say there must be a limit on Taiwan-mainland trade. In a recent interview with Hong Kong journalists, Shaw Yu-Ming, head of the Taiwanese government information office, said that Taiwan's exports to the mainland should not be allowed to reach 5 percent of the island's total exports, or "we shall be held hostage by the communists."

This limit on mainland trade would mean not allowing exports to exceed about $3 billion over the next year or so. Taiwan's total exports for next year are expected to reach about $64 billion.

But Shaw admitted that Taiwan cannot control the indirect trade that passes to the mainland through Hong Kong or other ports.

Thanks to its exports, Taiwan is the fifth-largest trading partner of the United States. It still relies on the United States for more than half of its export earnings, but analysts say that the island is being driven to seek other markets because of quotas, antidumping regulations and other measures designed to protect the American economy.

The United States' trade deficit with Taiwan is expected to surge beyond last year's deficit of $13.6 billion. As a result, Washington continues to support Taiwan's moves to make its currency appreciate against the dollar. The rise in value of Taiwan's dollar has made Taiwanese exports more expensive for American buyers.