US Secretary of State Colin Powell on Monday bombing in Riyadh:
"This was a well-planned terrorist attack, obviously. The facility had been cased as had the others, very well executed, and it shows the nature of the enemy we're working against," he said.
I could not understand this sentence, would appreciate your help.
When somebody cases something they very carefully and unobtrusively examine it, taking special note of its most important features. In this case, those planning an attack would have taken note of things like the approaches to the entrance, where the guards were stationed, and how many guards there were. The phrase "very well executed" means the plan was carried out well. In other words, they did a good job of doing something bad.