Washington ? President Bush unapologetically defended his approach to North Korea’s nuclear weapons program Wednesday, pledging he would not change course despite contentions that Pyongyang’s apparent atomic test proved the failure of his nearly six years of effort.

Bush rejected the idea of direct U.S.-North Korea talks, saying the Koreans were more likely to listen if confronted with the combined protest of many nations.

The president said he was not backing down from his assertion three years ago that “we will not tolerate nuclear weapons in North Korea.”

He said the United States “reserves all options to defend our friends and our interests in the region against the threats from North Korea,” a stance he said includes increased defense cooperation, especially on missile defense, with Japan and South Korea.

But he added, “I believe the commander in chief must try all diplomatic measures before we commit our military.”

The president appeared at a news conference in the White House’s Rose Garden in an effort to rescue a diplomatic drive to contain North Korea and to rebut charges he had been distracted by the Iraq war from the developing threat in Asia.

Aftershocks continue

Aftershocks of North Korea’s claimed nuclear test continued reverberating around the world.

A North Korean soldier observes the South through binoculars in the demilitarized zone at the truce village of Panmunjom. South Korea's military was reportedly readying for a nuclear conflict on Wednesday as the North warned that an international push to level sanctions on Pyongyang over its atomic weapons test would be an act of war.

At the United Nations, the United States and Japan pushed China and South Korea to support a sanctions resolution that would deliver what Bush called “serious repercussions” for Pyongyang, including cargo inspections.

Japanese officials, fearing for their nation just across the Sea of Japan from North Korea, took action on their own to choke off an economic lifeline for the impoverished communist nation, barring lucrative North Korean imports, most entries into the country by North Koreans and the presence of North Korean ships in Japanese ports.

South Korea, which fought a war with the North in the 1950s and like Japan regards Pyongyang warily, checked its readiness for nuclear warfare. The defense minister said Seoul could expand its conventional arsenal and the Joint Chiefs of Staff recommended improved defenses.

North Korea warns of war

North Korea, in its first formal statement since Monday’s test announcement, warned that new sanctions would be considered an act of war that would bring unspecified “physical corresponding measures.”

North Korea’s No. 2 leader Kim Yong Nam said more nuclear tests are possible. And while the Demilitarized Zone dividing the two Koreas remained calm, North Korean troops tried to provoke guards on the southern side by spitting across the line, making throat-slashing hand gestures and flashing middle fingers, according to a U.S. military spokesman.

In Washington, Democrats contended that Bush has mishandled North Korea by pursuing a strategy that led to a 400 percent increase in the nation’s nuclear capabilities under his watch.

“President Bush tries to talk tough, but he doesn’t act smart,” said Senate Minority Leader Harry Reid, D-Nev. “He insists on stubbornly following policies that don’t work, and it is time for a change.”

William Perry, a defense secretary under former President Clinton, said the U.S. government must abandon its desire for a new government in Pyongyang and agree to direct, one-on-one talks – even if on the sidelines of long-stalled six-party talks that also include China, South Korea, Japan and Russia.

“Until we make those two steps, we’re in a lost cause trying to deal with on North Korea,” Perry said in a conference call with reporters.

Annan calls for talks

The call for bilateral negotiations was echoed Wednesday by U.N. Secretary-General Kofi Annan from New York. But Bush again rebuffed the idea.

“One has a stronger hand when there’s more people playing your same cards,” he said in an hourlong news conference that was dominated by the North Korean crisis. “It is much easier for a nation to hear what I believe are legitimate demands if there’s more than one voice speaking.”

A day earlier, Republican Sen. John McCain had said Clinton was at fault for failing to take adequate action in the 1990s to stop North Korea from developing nuclear weapons.

Blame game begins

Bush gave scant attention to that domestic blame game, repeatedly turning the spotlight back on what he called “North Korea’s provocation.”

He said he learned North Korea can’t be trusted from the experience of the Clinton administration’s 1994 pact with Pyongyang, which offered energy help in return for a nuclear freeze but which the North secretly defied nearly from the start. He defended his decision to switch nearly immediately to a policy of refusing to talk with North Korea except when other regional players were also at the table.

“I appreciate the efforts of previous administrations. It just didn’t work,” he said.

The president acknowledged the difficulty of persuading nations such as China and South Korea to drop any resistance to a tough crackdown on North Korea by the U.N. Security Council.

“We share the same goal, but sometimes the internal issues are different from ours. And, therefore, it takes a while to get people on the same page. And it takes awhile for people to get used to consequences,” he said. “And so I wouldn’t necessarily characterize these countries’ positions as, you know, locked-in positions.”

Trade embargo wanted

The United States and Japan want the Security Council to impose a partial trade embargo, including strict limits on Korea’s weapons exports, a freeze of related financial assets and inspections of cargo to and from North Korea. They prefer that the sanctions fall under the portion of the U.N. Charter that gives the council the authority to back up its resolutions with a range of measures that include military action.

China is considered to have the most leverage with North Korea as its top provider of badly needed economic and energy aid. But both Beijing and Seoul worry a hard-line approach could destabilize the North and send refugees flooding over their borders.

“Peace on the Korean Peninsula requires that these nations send a clear message to Pyongyang that its actions will not be tolerated,” Bush said.