The attacks cast a shadow over the July 4th holiday for the 150,000 U.S. troops stationed in Iraq.
Several explosions rocked the base near Balad, 55 miles north of the capital, late Thursday, said Cpl. Todd Pruden, a spokesman for the U.S. military. The area is within a hot zone known as the "Sunni triangle," an area north and west of Baghdad where Saddam Hussein enjoyed his greatest support.
It is also an area where U.S. troops are conducting an operation to root out Saddam loyalists.
On Thursday evening, a sniper shot and killed a U.S. soldier manning the gunner's hatch of a Bradley fighting vehicle outside the national museum. The soldier was taken to a military hospital, but died of his wounds.
Hours before the attack, the national museum displayed several artifacts that were looted after the fall of Baghdad and later recovered. The museum also showed several items from the Treasures of Nimrud, which were found hidden in a bank vault weeks ago. Curators acknowledged that many of the museum's treasures remain unaccounted for.
U.S. soldiers have been beset by daily attacks from an increasingly bold insurgency, raising fear of a political and military quagmire just two months after President Bush declared an end to major combat on May 1.
At least 27 U.S. troops have been killed in hostile fire since Bush's statement.
In other recent developments:
In the north, American forces are holding joint celebrations with Kurdish officials. The Kurds celebrate July 4 as the anniversary of their first government's election in 1992.
On Thursday, U.S. troops near Baqouba, northeast of the capital, tried to lure attackers into an ambush on a stretch of road known as "RPG Alley" because of the frequent attacks on U.S. forces there. One suspect was killed and three captured in the operation, said Lt. Kurt Chapman, with the Army's 4th Infantry Division.
"We're trying to be a little bit more proactive and find them before they get us," Chapman said.
U.S. officials have said attacks on allied forces within Iraq are fueled in part by doubts about the fate of Saddam Hussein.
Also Thursday, Washington put a bounty of as much as $25 million - depending on the quality of the information - on Saddam Hussein's head and furthermore offered $15 million for information leading to the capture of either of his sons, Udai and Qusai.
The reward for Saddam matches the $25 million that Washington is offering its other top fugitive: Osama bin Laden, the al-Qaida leader missing since U.S. forces helped dislodge the Taliban regime in Afghanistan.
The last reported sighting of Saddam was on April 9, a day before the capital fell, in northeast Baghdad. He was the target of at least two major U.S. air strikes, but there was never any proof either was successful. Based on information from captured colleagues, officials believe they were not.
Saddam loyalists reportedly are warning Iraqis not to cooperate with American occupation authorities, saying the ousted leader will one day come back to punish those who do.
Scattered violence on Thursday wounded 10 American soldiers. During the skirmishes, which included convoy and sniper attacks, U.S. troops killed at least two Iraqis and wounded several more.