Ann: Trading Halt, page-19

IDA sends a copy of the award to the ICSID Secretary General. The Secretary certifies the award and promptly returns certified copies to all involved party's. IDA then furnishes a certified copy to a competent court or authority in a ICSID member state. No court can overrule the award decision. The decision is automatically upheld and becomes legally Recognised and Enforceable.

Even if Tanzania successfully claims State immunity commercial assets can still be seized.

Hope that explains it better.