The office - which was hit hard when the competition-winning designs were postponed more than two years ago - is now gearing up for the bulk of detailed design.
Delays to the £300 million project first emerged back in early 2004 (AJ 29.01.04) when it was revealed the development had already fallen two years behind its six-year design and construction programme.
According to reports, problems with the scale of the project held back the design process after NATO bosses asked SOM to increase the scheme's capacity following the entry of six new countries into the organisation in 2003.
The Belgian government had also demanded that the project move site, putting it in conflict with a Royal Belgium Air Force Officers' Club, which objected to the new building.
Because of the ongoing uncertainty over the future of the prestigious project at the time, it was rumoured SOM let go handfuls of staff, resulting in a plunge of 69 places down the 2004 AJ100 list of largest practices.