WASHINGTON (CNN) -- As the FBI prepared to brief reporters for the first time Thursday on the investigation into bombings at U.S. embassies in Kenya and Tanzania, new details have emerged indicating that the U.S. knew more than eight months ahead of the attacks that security in Nairobi was inadequate.

U.S. Ambassador to Kenya Prudence Bushnell warned the State Department, in cables sent in December 1997 and April or May 1998, that security at the Nairobi embassy needed to be upgraded.

One of the Bushnell cables said of the embassy: "The location is problematic, always has been. It's in one of the busiest streets in Nairobi, (at) the intersections of two major streets. The new embassies . . . have been built to different specifications from our embassy, which was constructed in the '70s."

In December of last year, Ambassador Bushnell told her supervisors she needed a new embassy.

An assessment team from the State Department's Bureau of Diplomatic Security made a trip to Nairobi in January and agreed the location of the embassy was undesirable.

On June 1, Bushnell, who was injured slightly in Friday's terrorist attack, got a written response to her calls for a new embassy from Undersecretary for Management Bonnie Cohen.

"In light of the current threat level and comparative recent construction of the building, a new building was ranked low in relative priority to the needs of other embassies," Cohen wrote.

A new embassy would have cost around $75 million and taken four years to build. According to the government's system of ranking countries by degree of danger, the Nairobi embassy was considered a low threat level and therefore other embassies took higher priority.

Meanwhile, in Nairobi Thursday, the FBI has scheduled a news conference for 10 a.m. local time to brief reporters on its inquiry as the focus shifts to investigators examining the blast site and witness accounts for clues to the identity of the bombers.