President Bush said Wednesday the United States would stop North Korea from transferring nuclear weapons to Iran or al-Qaida and that the communist regime would then face "a grave consequence."

Bush refused to spell out how the United States would retaliate. "They'd be held to account," the president said in an ABC News interview.

In light of North Korea's Oct. 9 test detonation of a nuclear bomb, Bush warned that any transfer of nuclear material elsewhere in the world by the North would be considered a grave threat to the security of the United States. He previously used "grave threat" in relation to Iraq's Saddam Hussein, whose government was toppled in the U.S.-led war in 2003.

"If we get intelligence that they're about to transfer a nuclear weapon, we would stop the transfer, and we would deal with the ships that were taking the — or the airplane that was dealing with taking the material to somebody," the president said.

Asked how he would retaliate, Bush would not be specific, "You know, I'd just say it's a grave consequence."

"The leader of North Korea to understand that he'll be held to account. Just like he's being held to account now for having run a test," Bush said.

The United States repeatedly has said it does not intend to attack the North. But the Bush administration also has refused to take any military option completely off the table.

Shifting to Iraq, Bush said intensifying violence now might be compared with the Tet offensive in Vietnam beginning in 1968. The Viet Cong and North Vietnamese armies undertook a series of attacks that shook America's confidence about winning the war and eroded political support for President Johnson.

"There's certainly a stepped up level of violence, and we're heading into an election," Bush said. But he added, "My gut tells me that they have all along been trying to inflict enough damage that we'd leave. And the leaders of al-Qaida have made that very clear."

Bush said al-Qaida was very active in Iraq. "They are dangerous. They are lethal. They are trying to not only kill American troops, but they're trying to foment sectarian violence.

"They believe that if they can create enough chaos, the American people will grow sick and tired of the Iraqi effort and will cause government to withdraw," he said.

The military said Wednesday that 11 U.S. troops died in combat amid a security crackdown in Baghdad, putting October on track to be the deadliest month for American forces since the siege of Fallujah nearly two years ago.

Bush said the news of casualties "breaks my heart" but said it is surrender "if you pull the troops out before the job is done."