The U.S. government on Monday remained firm on its disapproval of a trip to North Korea by former New Mexico Gov. Bill Richardson and Google Chairman Eric Schmidt.

They flew into Pyongyang earlier in the day, defying Washington's advice not to go there when efforts to punish the communist nation for its long-range rocket launch in December are under way.

In a one-sentence dispatch, the North's official news agency KCNA described the American visitors as part of a "delegation of the Google Corp. of the U.S."

The group is expected to stay in North Korea until Thursday before heading to Beijing.

The State Department called the trip "ill-advised."

"We continue to think the trip is ill-advised for the reasons that we stated last week," department spokeswoman Victoria Nuland said at a press briefing, when asked if there is any change in the department's view on the visit. "We just think the timing is bad."

It is still unclear whom the U.S. private team will meet in North Korea.

Richardson, head of the delegation, said he will discuss the issue of a Korean-American man, Kenneth Bae, detained there for more than two months.

The U.S. government has been trying to win his release through the Swedish Embassy in Pyongyang. The U.S. has no diplomatic representative in the nation as they have no formal diplomatic ties.

On Seoul-Tokyo relations, meanwhile, the State Department reiterated its basic position.

"We continue to hope that the countries in the region can work together to resolve their concerns over historical issues in an amicable way and through dialogue," Nuland said.

She was responding to a question about an apparent move by Japan's new leader, Shinzo Abe, to revise the so-called Kono Statement, an official apology by the Japanese government in 1994 for the Japanese military's enslavement of Korean and other Asian women during World War II.

Ostensibly, the Obama administration has maintained a neutral stance toward longstanding disputes between Washington's two key regional allies over their shared history and conflicting territorial claims.

South Koreans are deeply frustrated with Japan's continued claim to Dokdo, a set of rocky islets in the East Sea, and campaign to whitewash its wartime atrocities. (Yonhap News)