North Korea has much to do before the United States can remove it from its terrorism blacklist, U.S. President George W. Bush said Wednesday.

But Bush also expressed hope that Pyongyang's pariah status as a member of the "axis of evil" could some day be a thing of the past.

North Korea expects Bush to remove it from the U.S. list of terrorism-sponsoring countries as soon as next weekend, as promised when the North blew up its nuclear reactor cooling tower in June.

But Bush, speaking at a press conference in Seoul with South Korean President Lee Myung-bak, said North Korea must first agree to international terms for verifying its dismantlement efforts.

"I don't know whether or not they're going to give up their weapons," Bush said. "I really don't know. I don't think either of us knows."

Lee called North Korea "a very difficult opponent."

But, he added: "I have faith we will be able to move to the verification process, then to the next step."

The North, which exploded a nuclear device in 2006, is believed by experts to have produced enough weapons-grade plutonium to make as many as 10 nuclear bombs, and the U.S. has accused Pyongyang of running a second weapons program based on uranium.

Actual destruction of weapons — the ultimate goal of the six-party talks with North Korea that include the U.S. and South Korea — is months away at least.

Bush once branded North Korea as part of an "axis of evil," along with prewar Iraq and Iran, and spoke derisively of North Korean leader Kim Jong-il's treatment of his people and pursuit of nuclear weapons. The president said it is still "to be determined" whether Pyongyang can come off the list.

"In order to get off the list, the axis of evil list, the North Korean leader is going to have to make certain decisions," Bush said.