The Kuwaiti base is a logistics hub for US troops in Iraq
Kuwaiti officials say they have arrested six members of a "terrorist network", linked to al-Qaeda, who were planning to attack a US military base.
An interior ministry statement said that all six Kuwaitis had confessed to the crimes after they were arrested.
The statement said they had also planned to bomb the headquarters of Kuwait's internal security agency.
It mentioned other "important facilities" in the oil-rich emirate, but gave no further details.
Frank Gardner, BBC News
Kuwaiti opinions are divided when it comes to their country's close alliance with the US.
Older Kuwaitis, especially those who lived through the Iraqi invasion of 1990 and seven-month occupation, remain grateful to the US for saving their country.
But some younger Kuwaitis see the US in hostile terms, as invaders and occupiers of Iraq, as a friend of Israel and as an enemy to Muslims.
In 2005 Kuwaiti security forces broke up an al-Qaeda-linked cell said to be plotting attacks.
"The state security has uncovered a terrorist network following al-Qaeda, and includes six (Kuwaiti) citizens who have planned to carry out a plan to bomb Arifjan Camp, the state security building and other important facilities," the ministry said.
Al-Arabiya television said the group was plotting the attack for the Muslim holy month of Ramadan, which starts on about 20 August.
Camp Arifjan, a vast, purpose-built $200m (£120m) camp south of Kuwait City, is the main US base in Kuwait.
The heavily protected camp houses 15,000 US soldiers and is used as a logistics base for troops serving in Iraq.
Previous attacks against Americans in Kuwait include an incident in October 2002, when two Kuwaitis opened fire on US Marines, killing one.
The following year, a civil servant killed an American contractor and severely wounded another when he ambushed their car near a US army camp.
Six Kuwaitis and stateless Arabs were sentenced to life in prison in 2007 for planning attacks on US troops and Kuwaiti security personnel.