North Korea says it has nuclear weapons. Iran is rejecting a European proposal aimed at restricting Tehran's development of nuclear fuel, which it says is solely for the production of electricity, not a weapons program.

The Bush administration says it remains determined to use diplomacy in both cases, and top members of the U.S. Congress say vigilance is key.

The senior Democrat on the Senate Intelligence Committee, Jay Rockefeller of West Virginia, says both Iran and North Korea are, in his words, "very dangerous." He says in the case of Iran, there is extra reason for concern because of the history between the two nations.

"It's very focused against Israel. It is very focused against us. It has not forgiven us for overthrowing Prime Minister Mosadeq back in 1953. You know, the Shah and all of that. They really dislike us," he said.

Speaking on CNN's Late Edition program, Senator  said getting the latest intelligence information on Iran's nuclear ambitions is crucial.

"Everything we can do to gather intelligence information, no matter who is doing it among our intelligence and military agencies, is for the betterment, because we are stretched so thin," added Senator Rockefeller. "We need all the eyes on the ground that we can possibly get."

Mr. Rockefeller was interviewed along with the Republican chairman of the Senate Intelligence Committee, Senator Pat Roberts of Kansas. They were asked about a report in The Washington Post newspaper that quoted unnamed U.S., Iranian and European sources as saying unmanned U.S. surveillance aircraft, originating from U.S military facilities in Iraq, have been flying over Iran for almost a year.

Senator Roberts said some of the terminology in the report appears questionable. He would not confirm or deny the flights, saying only that his panel is keeping a close watch on all kinds of intelligence gathering activities.

"We will monitor that situation in the intelligence committee," he said. "How's that?"

North Korea was also a topic of discussion on the televised Sunday talk shows in the United States. Last week, North Korea said it had nuclear weapons, and demanded direct talks with Washington, which has said negotiations could only be held within the context of six-party talks that also include China, Russia, South Korea and Japan.

South Korea's foreign minister Ban Ki-Moon told CNN's Late Edition that his country remains committed to to multi-lateral talks with Pyongyang. And on the Fox News Sunday program, Senator Joseph Biden of Delaware, the top Democrat on the Senate Foreign Affairs Committee, suggested North Korea may be trying to get China and South Korea to put pressure on the United States.

"But the fact of the matter is, it has angered the Chinese government so far. It looks like it may have backfired," commented Mr. Biden.

Mr. Biden said that, overall, he agrees with the Bush administration that the six-party talks remain the best way to deal with North Korea.