President Yoweri Museveni deployed Uganda People’s Defence Force soldiers and police officers to patrol streets in Kampala after the US embassy in Uganda warned of a “specific threat” to attack Entebbe International Airport on Thursday between 1800 and 2000 GMT.
Although the embassy did not name any group, Al-Qaeda linked Al-Shabaab insurgents have claimed recent attacks in neighbouring Kenya and Djibouti, and at home in Somalia.
The move comes amid broader Western intelligence concerns that hundreds of Islamist radicals travelling from Europe to fight in the Middle East could pose a security risk on their return.
On Sunday, US President Barack Obama warned that “battle-hardened” Europeans who embrace jihad in Syria and Iraq threaten the United States because their passports mean they can enter without a visa.
Britain confirmed it is bolstering security at its airports in response.
Analysts said the move was likely linked to concerns Al-Qaeda in the Arabian Peninsula (AQAP) was passing on bomb-making expertise to militants fighting in Syria.
The fear is that militants with European passports could then bring these skills back home with them and launch an attack, experts add.