Assemble a group of whiskey drinkers and prime them with a glass or two, and the talk often wanders to that eternal whiskey debate: the Hillbillies versus Highlanders divide between Kentucky and Scotland.

But if the rising tide of Japanese and other Asian whiskeys entering the United States is any indication, "hills" may soon need to be stretched to include the Himalayas, "highlands" to encompass the Yamashiro Basin.

"A lot of people are surprised that the Japanese make whiskey, and it's really, really good whiskey - it's not something they just took to," says Mateo Hoke, bar manager at Nihon Whisky Lounge in the Mission District, which serves several styles of Japanese whiskey along with spirits from India.

"Just because it's new to the States and new to people's experience here doesn't mean it's a fly-by-night kind of thing. They take it very seriously, and they make some of the best whiskey in the world."

Japan's slow rise in the whiskey world started in 1923, when Suntory opened a distillery in Yamazaki, near Kyoto. Working with distiller Masataka Taketsuru, the company produced whiskey modeled on Scotland's famed spirits. Taketsuru left Suntory in 1934 to form a rival company, known today as Nikka.

Praise from critics

Broadly popular at home, Japanese whiskey has earned critical accolades in recent years as it has expanded into Western markets. Its image further boosted by the 2003 film "Lost in Translation," Japanese whiskey is becoming increasingly available in American bars at a time when single malts from other Asian producers are also entering the market.

Suntory currently exports 12-year-old and 18-year-old versions of its Yamazaki Single Malt, along with a limited 300-bottle edition of its Yamazaki 1984 anniversary whiskey. Last year, U.S. sales of Yamazaki reached 25,000 cases, and the company hopes to sell more than 30,000 cases in 2010.

In late 2009, Suntory launched its Hibiki 12-year-old blended whiskey in the U.S. and Europe, and the company may introduce single malts from another distillery, Hakushu, in coming years. Nikka, which distributes several styles of whiskey in Japan and Europe, including the acclaimed 21-year-old Taketsuru Pure Malt, is also planning to enter the U.S. market within the next year.

Liquor-store geography will become even more complex later this month. Five labels from Bangalore-produced Amrut single-malt whiskey enter stores in New York, Illinois, New Jersey and Massachusetts. It should be in California by the end of the year.

Whiskeys such as Hibiki and Taketsuru have garnered significant awards in recent years; in his "2010 Whisky Bible," whiskey expert Jim Murray rated Amrut's Fusion as the third-best whiskey in the world.

Until recently, Nihon was one of few bars that carried Asian whiskey. Today, Suntory's whiskeys can be ordered in San Francisco bars such as Alembic, 15 Romolo and Bourbon & Branch, as well as in places such as Bar Deville in Chicago and PDT in New York.

Japanese whiskey is finding enthusiastic fans.

"It has everything you love about American and scotch whiskeys, but there's a whole other world of flavor that takes some time to figure out," says Andrew Friedman, owner of Liberty, a Seattle bar with a growing selection of Japanese spirits.

Friedman notes that Japanese whiskeys have the honey, caramel and vanilla notes that are familiar to drinkers of bourbon or scotch. But Friedman says he also detects things that he doesn't find in Western whiskeys, including elements of sour apples and pears in single malts such as Yamazaki and Nikka's Yoichi, and a light floral aroma in blends such as Hibiki.

More subdued

Japanese whiskey starts as malted barley, but unlike some heavily peated scotch, the smoky character in the Japanese version is often subdued.

By using different strains of yeast and, in Suntory's case, wooden fermentation vats, producers tease different flavors from the grain before distilling in copper pot stills.

The young whiskey is then aged in oak; for Yamazaki, this means using three types of wood: some made from used bourbon barrels; others from used sherry casks; and others from Japanese mizunara oak, which lends a mildly spicy sandalwood character.

The three batches are mixed before bottling; the Yamazaki 12-year-old is largely from American bourbon barrels, while the 18-year-old is mostly from sherry casks. For Hibiki, a mixture of spirits from three distilleries is finished for its final two years in casks that formerly held Japanese plum-wine liqueur, then filtered with bamboo and charcoal, a process that lends a trace of fruity richness.

Japanese whiskeys can maintain a liveliness in the glass even at advanced ages, and the 18-year-old Yamazaki has become a favorite among bartenders.

"It has this kind of precision to it, and it has so much going on," Hoke says. "Some people will say that's a Japanese cultural characteristic coming through, of every layer being very clearly defined."

While Nihon mostly sells Asian whiskeys by the glass or bottle, some bartenders have found the flavor of Japanese whiskey particularly suitable to cocktails.

Yamazaki Holiday

At Rickhouse in the Financial District, bar manager Erick Castro says that during the winter holidays the bar was selling a case of Yamazaki 12-year-old every week, most of it mixed in a seasonal drink called the Yamazaki Holiday. The same whiskey also features in one of the most popular drinks on Rickhouse's current menu, the Mamie Taylor - a classic highball-style drink with lime juice and ginger beer.

"The Yamazaki is a little softer, a little more feminine, and it plays really well with the ginger," Castro says. "We also take pride in introducing people to new spirits, and this works really well in that drink."

Still, a large-scale embrace of Asian whiskey may not happen immediately.

"It's going to take a while for people to grok it," Friedman says. "Every day, we taste people on Japanese whiskey, and those people are amazed to find that everything they love about American and scotch whiskeys is there, along with another factor that's really surprising."