The next occupant of the White House better have an iron grip on the national-security challenges facing the United States in the geopolitical hotbed of South Asia well before taking the oath of office next January.

Why?

Because, like it or not, critical issues involving just the region's key countries of Pakistan, Afghanistan and India are likely to consume a good portion of the next president's time and effort from Day One.

The region is replete with Islamic terrorist and insurgent groups; weak, fragile governments; simmering international political tensions, and rampant narcotics production and trafficking (plus two of the world's nine nuclear arsenals).

The biggest challenge by far is Pakistan, a teeming country of 160 million. From its nuclear stockpile to its political turmoil, from the resurgent Taliban and al Qaeda to its testy ties with India, Pakistan will cost the next president a lot of sleep.

In the region, the most dangerous threat to US national security emanates from the al Qaeda holed up in Pakistan's Federally Administered Tribal Areas - including Osama bin Laden and his deputy, Ayman al Zawahiri.

The US director of national intelligence, Mike McConnell, told Congress in February that al Qaeda still poses a serious threat to our interests at home and abroad, and that its "central leadership" in Pakistan is its "most dangerous component."

He added: "The [tribal areas] serves as a staging base for al Qaeda attacks in support of the Taliban" as well as "a location for training new terrorist operatives" and "to maintain a cadre of skilled lieutenants capable of directing operations around the world."

Even more complications will come from Pakistan's new parliament, which will sit in strong opposition to the US-friendly President Pervez Musharraf - and likely push for his ouster. The former general's days could be numbered.

We can expect some level of counterterrorism cooperation to continue. After all, Pakistan saw 50 terror attacks in the last eight months that killed more than 800 people - an unprecedented level of bloodshed.

But the fact is, the Taliban and al Qaeda see Pakistan as easy pickings. The Taliban hopes to put one of the world's most populous Muslim nations under Sharia law. And al Qaeda is especially looking for a victory after taking major hits in Iraq - and would love to get its paws on some nukes.

Across the border, it's now been six-plus years since US forces hit the ground in Afghanistan to hammer al Qaeda and de-throne the Taliban. It's been tough sledding; attacks are up recently.

US intel chief McConnell says the Kabul government controls only about 30 percent of Afghanistan; the Taliban, another 10 percent; local tribes and "warlords" the rest. (Kabul quickly noted that many tribes at least cooperate with it.)

The Taliban took some new ground last year in the South and the West, using Pakistan's border areas as staging grounds. There's been no shortage of unproductive head-butting, name-calling and finger-pointing between Kabul and Islamabad as a result.

Another big problem? Drugs. Afghan narcotics production hit record "highs" last year - for the second straight year. Afghanistan grew 93 percent of the world's opium poppy by UN estimates, with the bulk of the "smack" going to Russia and Europe (and much of it passing through Pakistan on the way).

And with an export value of about $4 billion, last year's opium harvest made up more than a third of Afghanistan's combined total gross domestic product (GDP) of $11.5 billion.

The narco-trade undermines Kabul's efforts to stabilize the country; the Taliban gets payola for protecting poppy farmers and traffickers from the central government. Indeed, poppy production jumped most in provinces where the Taliban are dominant - their stronghold in Helmand province accounted for half of Afghan poppy production last year.

On top of the Taliban, the poppy fields and unbridled Afghan corruption, Kabul and Washington face NATO allies reluctant to help out more - all while trying to provide basic services and improve economic opportunity in the largely impoverished country.

The bright spot in the region (if there is one) is India - an economic dynamo and major military power. India's ascent is a net plus for US regional interests - not only because it provides an oasis of stability in comparison to neighboring Pakistan and Afghanistan but also because it keeps an eye on rapidly rising China.

Relations between the world's largest democracy and the world's most powerful have brightened significantly during the Bush Administration. Washington and Delhi have improved trade and defense ties and even inked a civilian nuclear energy deal (although it's stalled in the Indian parliament).

Not all is perfect, however. For example, Delhi is looking to build a gas pipeline from Iran, throwing an economic lifeline to Tehran despite its nuclear misbehavior.

And India's relations with Pakistan are often prickly, especially over the disputed territory of Kashmir. (Terror attacks by Kashmiri militants in India aren't uncommon.) But for now, the situation is stable, with both sides avoiding stoking a nuclear- or conventional-arms race.

The attacks of 9/11 brought South Asia into America's strategic headlights. It will stay there for the foreseeable future - and rightly so. The challenge for the next commander in chief will be to successfully manage the region with all its complexities.

Battling Islamic radicalism and terrorism, preventing loose nukes and promoting stability in South Asia are critical to protecting our homeland. But it won't be easy - the region is sure to remain, more often than not, a powder keg with a short fuse.

Peter Brookes is a Heritage Foundation senior fellow and former US deputy assistant secretary of defense.