The United States will continue to seek a U.N. resolution calling for referring North Korea to the International Criminal Court (ICC) for human rights violations despite Pyongyang's release of all three American citizens from detention, an official said Monday.

"Nothing has changed about our concerns about North Korea's abysmal human rights record. Nothing has changed about our concerns about their nuclear aspirations and capabilities," State Department spokeswoman Jen Psaki said at a daily briefing when asked if the U.S. continues to seek the U.N. resolution.

"Those issues remain ones that we will work with the international community on," she said.

North Korea released the last-remaining two American detainees -- Kenneth Bae and Matthew Todd Miller -- on Saturday after U.S.

Director of National Intelligence James Clapper made a secret trip to the communist nation and conducted negotiations on their release.

The North's decision was seen as aimed at improving the regime's image amid efforts led by the European Union to adopt a U.N. General Assembly resolution to punish the totalitarian regime for its human rights violations. The U.S. has voiced support for the initiative.

Clapper's trip to the North also had briefly raised hopes for a breakthrough in U.S.-North Korea ties, including a possible resumption of the long-stalled negotiations on Pyongyang's nuclear program. But American officials were quick to reject such speculation.

Psaki also said Clapper's trip does not mean an opening of nuclear or human rights negotiations with Pyongyang.

"Director Clapper went specifically because we knew that there would be a greater chance of bringing these two individuals home if we had a high level, Cabinet level official who was sent. But we did not want to indicate that this was the opening of any negotiations on nuclear issues," Psaki said.

"So it was appropriate that it was somebody with security credentials and not somebody who had been a negotiator or was working with other countries on nuclear issues or on human rights issues because it is not an opening for a dialogue on those issues," she said.

In Beijing, U.S. President Barack Obama also said that the North's release of the two Americans is no solution to a "core problem" between the two countries, and urged Pyongyang to demonstrate seriousness about giving up its nuclear program.

Obama also said that its takes more than "small gestures" like the release of the two for the two countries to resolve "a broader fundamental conflict" and that the U.S. has so far not seen "serious engagement on the part of Pyongyang to deal with that problem."

Meanwhile, Psaki confirmed a news report that Clapper's trip to the North was delayed by nearly two days because the plane carrying him broke down. But she declined to provide any further specifics, referring questions to his office.

The Associated Press reported earlier Monday that Clapper departed from Washington at 2 a.m. Tuesday on a C-40 aircraft and had expected to be in North Korea on Thursday, but the breakdown forced him to spend a day and a half in Hawaii while the plane was repaired. He did not arrive in North Korea until late Friday, the report said. (Yonhap)