By Noah Browning
The attack during Friday prayers, which killed 27 people including the bomber, appeared aimed at stoking sectarian hatred in the energy-rich Gulf. Islamic State claimed responsibility.
The coffins of victims of the bombing at the Imam Sadeq mosque in Kuwait City.Credit: Reuters
The three brothers were "parties to the crime of the sinful terrorist bombing that targeted the Imam al-Sadeq mosque in Kuwait," the SPA state news agency cited a security spokesman for the Saudi interior ministry as saying.
Two of the suspects, Majed and Mohammed al-Zahrani, drove across the border into Kuwait on the Thursday afternoon carrying the explosives for the attack in an ice cooler, Kuwait's interior ministry said in a statement.
They left after passing the materials to Abdul-Rahman Sabah Aidan, an illegal resident in Kuwait who reportedly drove the bomber to the mosque and is now in custody.
Investigators found the explosives were of the same type used in two suicide bombings on May 22 and May 29 against Shiite mosques in eastern Saudi Arabia, where the bulk of the kingdom's Shiite minority lives.
Majed was arrested in the western Saudi city of Taif while Mohammed was taken into custody after a shootout at a house near the Kuwaiti border in which two policemen were wounded. A third brother, whom the ministries did not name and whose precise role was not described, was arrested in Kuwait and extradited to Saudi Arabia.
A fourth brother lives in Syria and is a member of Islamic State.
The bombing was Kuwait's deadliest militant attack and the most lethal in any of the six hereditary-ruled Gulf Arab states since a campaign of al-Qaeda bombings was stamped out in Saudi Arabia a decade ago.
The attack has raised concerns about the number of young Saudi men willing to travel to attack Shiites in smaller Gulf Arab states and so make good on a threat by Islamic State to step up violence in the holy fasting month of Ramadan.
The Saudi branch of the militant group has said it wants to clear the Arabian Peninsula of Shiites and has urged young men in the kingdom to join its cause.
Reuters