Pyongyang's developing uranium-enrichment capability could be for making fuel rods for power-generating nuclear reactors -- but the more likely use is producing highly enriched uranium for bombs.

Yesterday morning, we woke to learn that North Korean artillery shelled -- without provocation -- the nearby South Korean island of Yeonpyeong in the Yellow Sea, killing nearly 20 soldiers and civilians.

That attack is just the latest major provocation this year. This spring, a North Korean mini-sub sank a South Korean warship, with the loss of 40-some lives.

What to make of these events?

Show of Strength: The revelation of the nuclear facility and the attack on the island are clearly meant to demonstrate that although "Dear Leader" Kim Jong Il will soon turn over the reins to his young and inexperienced son, Kim Jong Un, North Korea isn't to be messed with on the battlefield or at the negotiating table.

Indeed, the regime propaganda machine will likely insist that young Kim, who was elevated to four-star general in a recent ceremony despite a total lack of military experience, valiantly led the "counter-attack" against the South Korean "puppet regime."

What provocative act will the regime undertake next to burnish Gen. Kim's reputation?

Proliferation Problem: Any advance in North Korea's nuclear know-how is rotten news: Pyongyang is a prodigious proliferator. It's involved atomically with the likes of Syria and Burma and almost certainly Iran.

Indeed, news of its atomic activities will make North Korea a veritable nuclear Walmart, where bargain "shoppers" can go to stock up on nuclear knowledge, bombs or ballistic missiles.

China Challenge: Analysts talk of Beijing as key to managing Pyongyang, and they're probably right. China, as a major power in the 'hood and a big donor to North Korea, has a lot of sway.

But the Chinese have proven either unable or unwilling to rope in Pyongyang's bad behavior. Beijing's embrace of the regime after the ship sinking and ho-hum response to yesterday's shelling sure makes it look like the latter.

Plus, China's unwillingness to expose, confront or even criticize Pyongyang over its fancy new nuke plant shows Beijing is part of the problem and not the "responsible stakeholder" that many mistakenly hoped it would be.

Nukes 'R' Us: These provocations raise another fear -- that the North Koreans see their nuclear capability as having changed the security dynamic so drastically that they're no longer deterred by US-South Korean conventional forces.

Unafraid of conventional retaliation due its nuclear arsenal, the North may feel emboldened to push the envelope beyond its already calamitous conduct -- risking misperception, miscalculation and dire consequences indeed.

What all of this really means is that we'd better think long and hard about our national-security policy -- including such issues as defense budget cuts and our ability to fight big conventional wars overseas, not just unconventional ones.

We also need to ponder how the "New START" arms-control pact with Russia, now before the Senate for ratification, impacts our ability to handle the likes of North Korea, China and Iran. And developing a robust, comprehensive US missile defense just became indispensible.

If we're not careful, perceptions of American weakness, flabby national-security policies or an under-funded military will invite continued challenges and provocations not only by North Korea, but others, too.

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