The fierce debate on immigration ignores a crucial reality -- what is happening to the United States is only one piece, although a big one, of a much larger global picture.

That hit me a couple of weeks ago when I was in Singapore. The Southeast Asian island nation has long been hailed as an economic model, the business capital for the entire region.

But it is an economy facing demographic peril. Its small population of 4 million is shrinking, thanks to a very low fertility rate. Prosperous Singaporean couples work hard, have fewer children and worry about how to take care of their aging parents. By 2050, Singapore will have a median age of over 52, one of the oldest in the world.

Singapore's answer is to import labor. A third of its workforce are migrants, from construction workers to maids. One out of seven households employs a domestic worker -- low-paid women mostly from neighboring Philippines and Indonesia.

Singapore tries to lure "talents'' -- highly skilled and affluent migrants -- to stay permanently. But the men hauling bricks and the maids washing laundry are in a separate class of temporary guest workers, with no chance to join Singaporean society. If a maid becomes pregnant, she is shipped out within seven days. Employers have to post bonds that must be paid should their servants break the rules and try to stay, putting them in the role of migrant police.

Problems of abuse of domestic workers, including physical and sexual violence and confinement, are serious enough to have prompted a report last December by Human Rights Watch.

Singapore's dependence on migrant labor and its guest-worker policy may be at the extreme end but it's very much on the global spectrum. Labor, like capital and goods before it, is part of a global market. The movement of people across borders in search of wages and work, most of it from developing countries to developed, is growing at a phenomenal pace.

The numbers are staggering. From 1980 to 2000, the number of migrants living in the developed world more than doubled from 48 million to 110 million. Migrants make up an average 12 percent of the workforce in high-income countries. About 4 million migrants cross borders illegally every year.

The demand for labor is driven in part by a demographic disaster -- the falling birth rates of developed countries. Almost all of those countries now have fertility rates that are well below 2.1, the level at which a population replaces itself. At the very low end are Hong Kong (0.94), Korea (1.22) and Singapore in Asia (1.24), along with much of Eastern Europe.

Low fertility means shrinking workforces and aging populations. Without migration, according to a recent study, Europe's population would have declined by 4.4 million from 1995 to 2000. Immigration accounted for 75 percent of U.S. population growth during the same period.

This movement of people cannot be stopped, certainly not by hundreds of miles of fences or even by tens of thousands of border guards. It is an issue that cries out for global cooperation, for common policies that cut across national boundaries. Already, we can benefit from looking at what has worked -- and not worked -- elsewhere.

A Global Commission on International Migration, formed in 2003 by the United Nations secretary-general, has taken an initial stab. Their report, issued last winter, supports the growth of guest-worker programs.

The Senate immigration bill now up for debate includes a provision for a guest-worker program. The bill is clearly preferable to the punitive and ineffective approach of the House version. But the Singapore experience -- and previous guest-worker programs like the German import of Turks -- should prompt second thoughts about going down this road.

One problem is that the guests don't leave. The United States has its own experience with this in the bracero program to import farmworkers, and more recently with the supposedly temporary H1-B visas used so extensively by the high-tech industry here in Silicon Valley.

Most troubling to me, these programs create an underclass of migrants who are never assimilated, as happened in Germany. It sets us on the Singapore road, encouraging inhumane policing mechanisms. And it is a gilded invitation to employers to depress the wages and incomes of American workers, and not just in the dirty jobs that are supposedly so hard to fill.

The United States has been rightfully proud of a tradition that treats all immigrants as citizens in the making. Rather than guest workers, isn't it more American to set realistic immigration quotas and enforce them fairly?

The Middle East seems to occupy all the attention of our foreign-policymakers these days. But there are other parts of this globe that are probably more important, and potentially no less dangerous.

One of these is the Taiwan Strait. That narrow passage of water separates China from Taiwan, in Chinese minds a renegade province that must eventually be returned to its control.

The Chinese communist leadership dreads the prospect that Taiwan's democratically elected government might make the island's de facto independence a legal reality. China's heated military buildup in recent years is largely focused on creating the muscle to intimidate Taiwan and to seize the island if that fails.

A war across the Taiwan Strait makes the American top-five list of security dangers. The U.S. commitment to defend Taiwan is ambiguous, but it is not hard to imagine us being drawn into a conflict. And a war in the strait could easily expand to include Japan.

That is why the mayor of Taipei, Taiwan's capital city, got such a rousing welcome last week in Washington. Ma Ying-Jeou, or Mayor Ma as he is popularly known, does not threaten to upset the apple cart of cross-strait relations by pushing Chinese buttons with talk of independence, as the Taiwanese government loves to do.

Sitting down with Ma for breakfast as he made his way home to Taiwan, I could see why he was received with open arms at senior levels of the Bush administration. Ma, the leader of the opposition Kuomintang (KMT) party, is the front-runner in polls to win the 2008 presidential elections. He is articulate, a Harvard Law School graduate with movie-star looks and a reassuring message for Americans.

"We support maintenance of the status quo, which is also U.S. policy,'' he told me.

A KMT-led government would not waver from the "Five Nos,'' a pledge made by President Chen Shui-bian not to take steps toward a declaration of independence. He offers in addition a program of ``Five Dos'' should it return to power.

First, the KMT hopes to resume negotiations with the mainland, based on a 1992 agreement that while there is one China, there are different interpretations of what that means. Second, it will try to reach a peace agreement, lasting from 30 to 50 years. Third, the KMT would expand the already massive economic ties between Taiwan and the mainland into a possible cross-strait common market. Fourth, the KMT would try to create a formula to allow Taiwan to participate in international affairs, including global organizations, short of being an independent state. Last, it would expand cross-strait cultural and education exchanges.

Ma downplays the threat from Beijing these days. "Their goal is no trouble,'' he told me. "They are not interested in unification right now.'' But, he said, the Chinese do worry about "the further drifting away of Taiwan.'' That drift, he fears, could inadvertently force a conflict that might drag in the United States.

That charge is aimed at the government in Taipei. And it is a concern shared by U.S. officials who are visibly unhappy these days with Chen. The warm reception for Ma was intended to send that message to Taipei -- and also to Beijing, ahead of the visit next month of Chinese leader Hu Jintao.

Reassuring as Ma's words may be, there are reasons to be cautious about his message and his prospects.

Taiwanese nationalism may rattle the status quo, but so does China's military buildup. As does the failure of Taiwan to adopt a significant U.S. defense package, offered five years ago, to counter that buildup. The KMT blames the current government for this impasse but the party, which now controls the legislature, has blocked passage of the budget.

Deepening economic ties with China are a market reality, as Taiwan's electronics industry shifts production to low-wage China. But ultimately that could make them another Hong Kong, a satellite of Beijing that must bend to its political will.

Taiwanese are deeply divided. The KMT, the party of mainlanders who fled to the island after the communist victory in 1949, ruled Taiwan for decades as the exiled government of China. But democracy, which came in the 1990s, brought to power native Taiwanese who want to preserve their separate identity.

Ma may prove to be a political leader who plays better in Washington than back home. But if Taiwanese embrace his vision of the status quo at the ballot box, all the better. Ultimately, his mandate must come from Taiwanese, not Americans.

The nuclear deal reached during President Bush's recent visit to India unleashed a predictable wave of criticism. From editorial and op-ed pages to Congress, led by the left but supported on the right, the administration has been assailed for making a bad bargain.

Under the agreement, which still needs congressional approval, India would open much of its nuclear facilities to international inspections in return for gaining access to the world's supplies of uranium and U.S. nuclear expertise.

The attacks on the deal reflect the view of the nonproliferation lobby -- the experts and policymakers whose central concern is to stop the spread of nuclear weapons. I share their aim. But American arguments against the India deal are misleading and only expose the deep contradictions, if not hypocrisy, of our own nuclear policies.

There are two main criticisms of the agreement: first, it undermines the Nuclear Nonproliferation Treaty, the NPT, and second, it permits, even encourages, India to expand its nuclear weapons production.

The NPT issue is particularly sensitive at a time when the international community is trying to persuade Iran to give up certain nuclear technologies which many nations fear are part of a secret bomb program.

The NPT created two sets of global rules -- one for the five nuclear weapons powers it recognizes (China, the United States, Russia, Britain and France) and another for everyone else. The five, for example, allow only "voluntary'' international safeguards on their civilian nuclear facilities. They have no obligation to open their military programs to any kind of scrutiny. And the NPT places no real limits on their arsenals, other than a vague commitment to reduce and eventually eliminate all nuclear weapons.

The rest must open their nuclear energy programs fully to international inspection and agree never to build bombs. In exchange, they gain access to the peaceful uses of nuclear energy.

Iran -- and North Korea -- made that bargain and can be held to account for breaking the rules. But India consistently regarded that as an unequal trade-off and never signed the NPT; neither did Pakistan and Israel, two other nuclear weapons states.

India's nuclear program is the product of decades of largely indigenous effort; it did not result from secretive proliferation in violation of the NPT.

The deal with India turns the five into six. It treats India as a de facto member of the inner club. The deal would require changes in U.S. law to remove existing restrictions on the transfer of nuclear energy technology, changes that would allow India to be treated no differently from China.

That does not weaken the NPT -- it strengthens it. It brings it more into accord with reality and gives India a stake in a system it had previously rejected as unfair. It paves the way for India to join the Nuclear Suppliers Group, the international organization that controls nuclear exports.

The critics are right that the deal enables India to expand its production of fissile materials to make nuclear warheads. Eight of India's 22 power reactors will remain outside international controls, along with a new breeder reactor. The Indians fought for that exemption because they feel their nuclear arsenal may not be large enough to deter a nuclear first strike by Pakistan or China in the future. Critics fear that with increased access to uranium and limited inspections, India will set off an arms race in South Asia.

Again, the agreement simply treats India like the five. Nonproliferation experts claim that unlike India, however, the five have halted their production of plutonium and highly enriched uranium that could be used to build new weapons. This is true, but misleading.

The five have massive stockpiles of fissile material built up during the Cold War. "If I've got a full pantry, it's easy for me to swear off trips to the supermarket,'' said Michael Levi, an arms-control expert at the Council on Foreign Relations.

Moreover, the United States has embarked on a new program to rebuild its nuclear weapons production capability, including creating new facilities to produce plutonium cores for warheads and to assemble them.

India has agreed to back a global pact to cut off fissile-material production. But the Bush administration does not support a treaty that would actually verify this is taking place. And the U.S. Senate has refused to ratify the Comprehensive Test Ban Treaty that would permanently halt any new testing of nuclear weapons.

A Congress that can support those policies is hardly in a position to challenge the administration's agreement with India. Rather than block the U.S.-India deal, it makes more sense to improve it. This could include reaching agreements for cooperation between the two countries to ensure the safety and security of nuclear facilities, including those for military purposes, suggested Stanford Professor Scott D. Sagan, a leading expert on nuclear safety and nonproliferation. "Reducing the risk of terrorist theft of nuclear materials or weapons in India would also help protect the United States,'' argues Sagan.

Beyond that, the six acknowledged nuclear powers should begin to seriously fulfill their part of the NPT bargain -- to cap fissile-material production, to ban nuclear testing, and to eventually radically reduce stored arsenals of nuclear weapons and materials.