The U.S. ambassador to Saudi Arabia says Riyadh failed to fulfill Washington's request for more security around western compounds ahead of Monday's bombings.
Ambassador Robert Jordan says U.S. officials asked the Saudi government to increase security earlier this month after learning of a potential threat.
Saudi Foreign Minister Prince Saud al-Faisal says Saudi security was too lax, despite intelligence information that some kind of attack was being planned. He said Wednesday Riyadh must learn from its mistakes and improve its performance.
Saudi officials say the attacks claimed 34 lives -- including at least seven Americans and nine attackers.
The Saudi government says 15 Saudis carried out the attacks. Riyadh says the blasts are linked to the 19 al-Qaida operatives who engaged in a gunbattle with police in Riyadh last week. Police seized a large quantity of weapons and explosives after that battle, but the men got away.
No group has claimed responsibility for the blasts, which devastated three Riyadh housing compounds inhabited mostly by Westerners. Saudi investigators are searching through the rubble looking for clues to the attackers' methods and identities. The United States is sending an FBI team to Saudi Arabia to help in the investigation.