The chairman of the Joint Chiefs of Staff said Sunday that the release of the Lockerbie bomber was clearly "political," as new questions were raised about how involved British Prime Minister Gordon Brown was in the decision.
Adm. Mike Mullen said he was "appalled" by the decision to release Abdel Baset al-Megrahi, the Libyan convicted of killing 270 people in the 1988 airline bombing.
Megrahi, who is terminally ill with prostate cancer, was released Thursday on compassionate grounds by Scotland's justice minister.
"Well, this is obviously a political decision, which is out of my lane. But I mean, just personally, I was appalled by the decision," Mullen said.
Mullen joins a number of other high-profile U.S. officials who have condemned the decision.
"I am outraged at your decision, blithely defended on the grounds of 'compassion,"' he wrote.
A statement from Scotland's government on Saturday noted Mueller has "strong views" because of his involvement in the case. "But he should also be aware that while many families have opposed Mr. MacAskill's decision, many others have supported it," the statement said.
But Britain's prime minister was under scrutiny, as the Guardian reported that a letter he sent to Libyan leader Muammar al-Qaddafi indicated that the two discussed details of the release six weeks earlier.
Al-Qaddafi on Friday also thanked Brown and Queen Elizabeth II for "encouraging the Scottish government" to take their decision -- a claim denied by both Downing Street and Buckingham Palace.
The British and Scottish governments have denied that they struck a deal with Libya to free the Lockerbie bomber in return for greater access to the country's oil and gas.
Brown's office insists that the government in London does not meddle in the work of Scotland's administration -- which has wide powers over domestic issues, but has no say in areas such as defense or foreign affairs.
Mullen spoke on CNN's "State of the Union."
The Associated Press contributed to this report.