The US government has offered a $10m (£8m) cash reward for information about Mohammud Abdi Aden, the alleged mastermind of the 2019 attack on a hotel and office complex in the Kenyan capital, Nairobi, in 2019.
Mr Aden was allegedly part of the cell that planned the DusitD2 hotel attack, which resulted in the deaths of 22 people.
The Somalia-based militant group al-Shabab said it carried out the assault.
The US says Aden is wanted alongside other suspected militants.
The reward is offered with the full support of Kenyan authorities.
Several people accused of playing various roles in the run-up to the attack have been arrested and arraigned in court. But no-one has been convicted on charges linked to the attack.
Earlier this week, the US offered a $10m bounty for any leads on Maalim Ayman, the leader of al-Shabab’s military wing in Kenya.
He is wanted for his alleged role in the attack of an army base hosting Kenyan and US forces near the border with Somalia.
The US has been a key ally of Kenya on the war against terror.
Al-Shabab has carried out several attacks in Kenya saying they were in retaliation for sending troops into Somalia in 2011 as part of the African Union mission to fight the militants.