Uganda beefed up security in its capital city Kampala and the country’s main airport on Thursday after the US warned its citizens in the east African nation of a “specific threat” of an attack on Entebbe International Airport.

A message on the U.S. Embassy website cited information from Uganda’s police force that said an  attack could take place at the airport between 9 p.m. and 11 p.m. The embassy however did not name any group, but Al-Qaeda linked Al Shabaab insurgents from Somalia have previously issued threats that they could attack the country.

Al Shabaab have in recent months claimed attacks in neighboring Kenya and Djibouti, and at home in Somalia.

“The US Embassy has received information from the Uganda Police Force (UPF) that according to intelligence sources there is a specific threat to attack Entebbe International Airport by an unknown terrorist group today, July 3…. Individuals planning to travel through the airport this evening may want to review their plans in light of this information,” the statement reads in part.

A spokesman for Uganda’s Civil Aviation Authority told Reuters it had issued an alert on Wednesday, but did not give details.

President Yoweri Museveni heeded to the warning and deployed Uganda People’s Defense Force soldiers and police officers to patrol streets in Kampala.

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 Friday The Monitor said counter terrorism police and military officers were manning the city centre and all major entrances to the capital. They had also set up barriers and closed some roads before carrying out searches.

Kampala Metropolitan Police spokesman, Patrick Onyango, said the action was to prevent terror attacks during the World Cup finals. During World Cup finals in 2010, Al Shabaab launched two bomb attacks in Kampala killing 78 people.

The Monitor further said that Uganda’s Inspector General of Police, Gen. Kale Kayihura, had warned last week that Entebbe Airport was at the risk of being attacked by terrorists and they (terrorists) had already carried out trial runs on how they would carry out the attack.