White House press secretary Robert Gibbs said the United States had repeatedly asked Scotland to keep Abdel Baset al-Megrahi in custody. Gibbs said: "On this day, we extend our deepest sympathies to the families who live every day with the loss of their loved ones."
The State Department released a brief statement by Secretary of State Hillary Rodham Clinton, who is on vacation, saying she is "deeply disappointed" by the decision to release al-Megrahi.
"We have continued to communicate our long-standing position to UK government officials and Scottish authorities that Megrahi should serve out the entirety of his sentence in Scotland," Clinton said.
Attorney General Eric Holder released a statement saying he was "extremely disappointed" with the release.
"The interests of justice have not been served by this decision," it said. "There is simply no justification for releasing this convicted terrorist whose actions took the lives of 270 individuals, including 189 Americans."
Holder's statement said that al-Megrahi "did not show and has not shown compassion for innocent human life, and as we communicated to the Scottish authorities and the UK government, it continues to be our position that he should have been required to serve the entire sentence handed down for his crimes."
According to a White House official, Clinton and Holder were among those to directly convey to the U.K. and to Scottish authorities the view al-Megrahi should serve out his term in Scotland, reports CBS News White House correspondent Peter Maer.
But, as CBS News legal analyst Andrew Cohen notes, al Megrahi "was in a Scottish prison subject to Scottish law and that means that Scotland gets to make the final call. Remember, many Europeans don't care for the way the U.S. dispenses justice, especially when it comes to capital cases. So this is a situation where the tables are turned."
Scottish Justice Secretary Kenny MacAskill said the order to release al-Megrahi grew out of the convicted bomber's deteriorating health. He has prostate cancer and is not expected to live much longer.
He had served only eight years of a life sentence in Scotland for the December 21, 1988, bombing over the town of Lockerbie.