WASHINGTON (AP) – President Bush said Thursday it is hard to read North Korea’s motives in firing a missile with the potential to hit the United States or Canada, but said the U.S. cannot afford to misjudge the situation.

“I think we’ve got to plan for the worst and hope for the best,” Bush said.

Bush stressed that the United States is seeking a diplomatic solution to the nuclear standoff with North Korea. He cautioned that diplomacy will take time.

The president said he was pleased that leaders of China, South Korea, Japan and Russia, in telephone calls during the past few days, agreed that the reclusive communist regime should not be allowed to possess nuclear weapons.

“My message was that we want to solve this problem diplomatically, and the best way to solve this problem diplomatically is for all of us to be working in concert,” Bush said.

Bush said the nations’ message to North Korean leader Kim Jong Il was clear: “We expect you to adhere to international norms. We expect you to keep your word.”

Asked for an assessment of the reclusive North Korean leader, who is variously described as quirky, eccentric or even unbalanced, Bush struck a thoughtful pose.

“It’s hard for me to tell you what’s on his mind. He lives in a very closed society,” marked by concentration camps and starving people, Bush said.

“What we don’t know is his intentions,” Bush said.

North Korea test-fired seven missiles this week in defiance of warnings from the United States, Japan and China, its last major ally. The firings included a long-range Taepodong-2 missile _ the object of intense international attention for more than a month _ that failed 42 seconds after liftoff, suggesting a catastrophic failure of the rocket’s first, or booster, stage.

At the United Nations, there were differences over a Japanese-backed draft resolution to sanction North Korea. U.S. Ambassador John Bolton said the measure had “broad and deep support,” but Russia’s deputy U.N. ambassador told The Associated Press that Moscow would not back sanctions, as the resolution calls for.

Instead, Russia wants the council to pass a nonbinding presidential statement with the goal of getting North Korea back into six-party talks on its nuclear program.

While agreeing that North Korea’s missile tests were a provocative act, Canadian Prime Minister Stephen Harper, who appeared with Bush at the news conference, said Canada was not ready to reopen discussions about joining the U.S. missile shield. The shield involves basing missiles capable of taking out incoming missiles launched by terrorists or rogue states _ although the system isn’t designed to foil a mass attack by a major power.

Opponents of the missile scheme _ including Canada’s former Prime Minister Paul Martin _ say it won’t work and risks kicking off a new international arms race. Bush said he did not broach the issue with Harper.

“I didn’t bring it up,” Bush said. “I figured if he was interested, he would tell me.”

Bush said the more isolated North Korea becomes, the bigger the threat is to the world.

“And it’s just really important for, for the American president to see the world the way it is, not the way we would hope it would be.”

In Beijing, the Chinese Foreign Ministry said Chinese President Hu Jintao urged calm and restraint in dealing with North Korea during the telephone conversation with Bush.

Hu told Bush that China was “committed to maintaining peace and stability in the Korean Peninsula and opposed to any actions that might intensify the situation,” the ministry said in a statement posted on its Web site.

“Under the current complicated circumstances, it is extremely necessary to maintain calm and restraint,” the statement cited Hu as saying. “At present, we are willing to communicate and consult on the matter with all parties.”

The conversation took place the same day that China announced it will send a diplomatic troubleshooter to Pyongyang and urged diplomacy _ not threats _ as the best way to alleviate tensions the tests.

Earlier Thursday, the White House said any attempt by North Korea to gain concessions following its missile tests will be rebuffed by the U.S. and the four other nations pressuring Pyongyang to give up nuclear weapons.

In a statement about Bush’s calls to the leaders of South Korea and Japan, the White House stressed the need for a unified response to North Korea in the U.N. and elsewhere. Bush is seeking a diplomatic solution through six-way talks among North Korea, South Korea, Japan, China, Russia and the United States that were suspended last fall.

The talks produced a breakthrough agreement last September that would give North Korea economic rewards in exchange for dismantling existing weapons and swearing off new ones. North Korea walked away from the talks in December after the United States imposed sanctions it says are unrelated to the nuclear deal.

The administration brushed off blustering warnings from North Korea, including a new threat to test-fire additional missiles.

“We’re certainly not going to overreact … to these wild statements out of Pyongyang and North Korea,” said Undersecretary of State R. Nicholas Burns. “We’ve seen them before.”

The North Korean Foreign Ministry, in a statement carried by the state-run Korean Central News Agency, insisted that the communist state had the right to missile tests and argued the weapons were needed for defense.

The South Korean press reported Thursday that the North had three or four short- or medium-range missiles on launch pads ready for firing.