The Kuwaiti army says it has detained a number of soldiers suspected of plotting to attack "friendly forces" - a reference to US troops there.
About 25,000 American soldiers are currently stationed in the emirate.
Kuwait is also the transit point for multinational forces travelling to and from neighbouring Iraq.
The US embassy in Kuwait City said last month that it had credible information that terrorist groups were planning attacks in the region.
"The military intelligence security service is questioning some soldiers, following information concerning their intention to carry out an attack on friendly forces," Kuwaiti army spokesman Yousef Abdelrazzak al-Mulla was quoted as saying by the Kuna news agency.
The spokesman said that the number of the soldiers detained was fewer than five and that they could face court martial.
He added that some of those interrogated had already been released because they were cleared from involvement in any plots.
Reports from Kuwait say the arrests were made last week and that a number of civilians had also been detained, the BBC's Heba Saleh says.
Security beefed up
Kuwait is one of the most pro-American countries in the Arab world, as most people there remain grateful to Washington for liberating their country from the Iraqi occupation in 1991, our correspondent says.
But even so, she says Islamic militants in the emirate resent the American military presence in their country which remains the main staging post for coalition troops going into Iraq.
Kuwait has stepped up security following the US embassy warning, stationing armed military and police vehicles around Western embassies, oil facilities and also on major street junctions.
A group of 20 Kuwaiti men are already being tried for plotting to attack US forces in Iraq and Kuwait.