WASHINGTON, Dec. 31 (Xinhua) -- U.S. President Barack Obama was briefed Thursday about the preliminary reviews he ordered into the failed plane bombing plot, and ordered a meeting with relevant agency heads Tuesday, according to the White House.

    The president, who is vacationing with his family in Hawaii, said in a statement he will meet personally with relevant agency heads Tuesday in Washington to "discuss our ongoing reviews as well as security enhancements and intelligence-sharing improvements in our homeland security and counter-terrorism operations."

    He spoke with his Homeland Security and Counter-terrorism adviser John Brennan about preliminary assessments from the review into human and systemic failures that occurred leading up to the attempted Christmas Day plot.

    He said Brennan also briefed him on the "government-wide efforts at continued vigilance on homeland security and counter-terrorism efforts."

    In a separate call, Obama spoke with Homeland Security Department Secretary Janet Napolitano to receive an update on both the Department review of detection capabilities and the enhanced security measures in place since the Christmas Day incident.

    Obama is to receive assessments about the reviews from several agencies Thursday night. He is expected to study the assessments overnight and through the course of the new-year weekend.

    HUMAN AND SYSTEMIC FAILURES

    The president admitted that a mix of human and systemic failures have contributed to the occurrence of the incident on Christmas Day, and he ordered reviews into the incident.

    Umar Farouk Abdulmutallab, a 23-year-old Nigerian, attempted to set off an explosive device attached to his body on a Delta/Northwest flight from Amsterdam, The Netherlands, to Detroit, Michigan, on Dec. 25.

    The incident raised serious questions on how the suspect boarded the plane with explosives, and how the U.S. security agencies missed signals prior to the incident, which could prevented the suspect from boarding the plane.

    Abdulmutallab's father warned the U.S. embassy in Nigeria last month of his son's radicalization. However, the U.S. intelligence agencies only added Abdulmutallab's name to a terrorist watch list that includes names of persons possibly connected to terrorist groups but not automatically subjected to more security screening at airports. Abdulmutallab's visa to the United States was also never revoked.

    Even without the father's warning, "there were bits of information available within the intelligence community that could have and should have been pieced together," Obama conceded.

    According to U.S. media, electronic communications intercepted from Yemen by the National Security Agency had warned an Nigerian was training for an al-Qaeda attack. Other communications indicated there was a plan for a Christmas Day attack.