THE United States is struggling to counter growing discontent with the 100,000 American troops now based in Japan and South Korea.
For the first time in a generation, protesters have shouted ''Yankee go home'' in Japan, where most of the troops are based, and Washington has heard them.
In recent weeks a host of American officials, including Vice President Al Gore, have visited Japan to affirm the importance of the US-Japan security alliance. President Clinton was to have come last weekend, until the budget crisis delayed the visit to early next year.
Defense Secretary William Perry came to the region three weeks ago to mollify Japanese and South Koreans on two issues that stirred resentment in recent months. In Japan he apologized for the rape of an Okinawan schoolgirl involving three American servicemen. In Seoul he promised quick revisions to a controversial agreement that governs the stationing of US troops there.
The Okinawa case, in particular, continues to rankle the Japanese.
Last weekend Mr. Perry had to ask for the resignation of the commander of all 330,000 American forces in the Pacific, Adm. Richard Macke, for saying that the three servicemen should have hired a prostitute instead.
American officials and like-minded Asians insist that America's ''forward deployment'' has kept this part of the world safe for democracy and growth. The US and Japan have reviewed their security arrangements this year, and Perry says the status quo is appropriate for the ''foreseeable future.''
But in the decades since the US military first ensconced itself in Japan after World War II, and in South Korea a few years later, much has changed:
* South Korea and Japan are, for lack of a better term, maturing. Many Koreans feel they deserve more respect from the United States. Some Japanese argue that they should stop relying so heavily on the Pentagon for their security.
* Tolerance for American troops is decreasing. Okinawans are already demanding a phased reduction of American troops on their islands, and recent political reforms could create similar situations in South Korea.
* The American role in both countries has evolved. The US military mission in the region has grown fuzzier, and Washington has developed a new identity as an irascible trade partner.
As long as a communist North Korea exists, few South Koreans will seek an US withdrawal. Many Japanese, too, feel that a reduced US presence would cause more problems than it would solve. But as analysts in both the US and Asia observe, insisting on keeping the status quo may prove untenable.
The biggest problem, as one Western diplomat in Seoul puts it, is that ''it seems implicitly to be demeaning to have to have foreign troops'' in one's country. When the US solidified its presence in Japan and South Korea, one was a shattered enemy, the other an poor country that America had protected from invading communists.
Japan now has the world's second-most-important economy, despite the recession of the past four years. It got there partly because the security alliance absolved the country of having to invest too much in its own defense. This arrangement has pleased many in Asia, who worry that a militarized Japan will inevitably become a belligerent Japan.
But the Japanese increasingly wrestle with the concept of maturity. Politicians and opinion leaders often speak of the need to develop more ''mature'' political and economic systems. In essence, they want freedom from the domineering bureaucracy that has long run the country.
''The security system of Japan itself should be rebuilt. Security in Asia should also be made less dependent on the US,'' Kazuo Yoshida, a professor of politics at Kyoto University, wrote this summer.
In South Korea the issue is recognition. ''Koreans feel that after the enormous economic development of the past few decades we deserve to be treated with a little more respect, and the feeling is we aren't getting it,'' says a retired South Korean diplomat.
A subway brawl between American troops and Koreans in Seoul this May prompted a public outcry over the legal protections afforded US military personnel in South Korea, especially provisions that allow the US to maintain custody of personnel suspected of committing crimes off base. Protesters reiterated old characterizations of the American military as an occupying force whose soldiers commit crimes with impunity.
That is an extreme and exaggerated view, but the government formally requested that the Status of Forces Agreement (SOFA) between the two countries be revised. This month Defense Secretary Perry promised that South Korea's most pressing concerns would be addressed by early next year.
North Korea's menacing presence makes more comprehensive evaluations of the US presence academic, at least for now. ''We don't want to reduce the number of US forces in Korea,'' says Kim Wook, an official of the American affairs bureau in South Korea's foreign ministry. ''But we have to wait and see, depending on the security situation in the Korean peninsula and in East Asia as a whole. We may want to adjust in the future.''
The US military's mission in East Asia has also changed;.US policymakers have to find new reasons to justify the troops now that the Soviet Union is a memory. In Tokyo this month, Perry warned of the continuing threats to the interests of the US and Japan: rogue regimes, weapons of mass destruction, and terrorism.
But in places like Okinawa, a southern island prefecture that hosts the majority of American troops and facilities in Japan, many people feel that these rationales are not convincing.
It has not helped the US cause that America is now often seen as a demanding trade partner. ''The American government and its trade officials treat us very harshly,'' says political scientist Lhee Ho-Jeh of Korea University in Seoul, referring to US efforts to open South Korean markets.
Concurrent with these developments has been Washington's insistence that South Korea and Japan pay more of the costs of stationing US troops. Recently, the US has concluded agreements with both countries that include increases in the amounts they contribute.
The rape in Okinawa and the Seoul subway brawl point up the most controversial aspect of the US military presence: the difficulty of hosting a foreign army. The incidents are not comparable in terms of severity, says the Seoul-based Western diplomat, ''but the emotion surrounding the presence of the troops in both countries is probably roughly parallel.''
The emotions have grown stronger as American troops have become younger and less educated. Observers in both countries refer to a decline in the ''quality'' (code for ''race'') of US soldiers since the military became all-volunteer. ''We are homogeneous societies,'' says a South Korean academic who insisted on anonymity, ''so black soldiers especially are not welcome.''
This issue also reflects a generation gap, in that younger Japanese and South Koreans do not remember America as the leader of the free world. And in both countries, the shrinkage of the US dollar in the past three or four decades means US bases generate less local business.
Okinawans want change
Domestic factors also create dissatisfaction over the US military presence. Okinawa's governor, for instance, has made it clear that his constituents are no longer willing to put up with a disproportionate number of American troops in their midst. The US and Japan this week began a high-level review of the American deployment in Okinawa, but relocating bases will not be easy.
South Korea this year conducted its first local elections in 30 years, meaning that local leaders now answer to voters and not to the central government. Mr. Kim, the South Korean Foreign Ministry official, notes that US military installations are in the heart of major cities, such as Seoul, Pusan, and Taegu. ''The US camps can become an obstacle in city development planning,'' he says. ''A lot of complaints are being made.''
US officials say they have been disappointed that there have not been more expressions of support in recent months from regional political figures.
Last weekend 18 government leaders from the Asia-Pacific region, most of them heads of state, met in Osaka, Japan, to decide on measures to promote freer trade and investment. The difficulties that have arisen over the US military presence in the region lurked in the background, and Mr. Gore and Japanese Prime Minister Tomiichi Murayama both affirmed the stability of the relationship.
Other leaders were more circumspect. One leader, a closer friend of the US, Philippine President Fidel Ramos, told the Japanese daily Yomiuri Shimbun that the US must maintain its ''productive presence'' in the region.
''On the other hand,'' he added, ''from my experience, it is more economic interdependence, not military arms, that will ensure security of the region.''