Regarding security comments, Vonmessa, did you see how many police where present just in the immediate explosion areas? I counted 8 uniformed cops that were there within 10 seconds of the blast, on the video on uTube that is about 30 yards from the explosion. How much more security can you have? There were cops everywhere, literally every 20 yards along that part of the route by the looks of the video. Also, many people today are saying that prior to the bombings there was a HUGE police presence, with many dogs, so many, that people were asking if some sort of event had happened, to which the police were replying "it's a drill" - all this prior to the explosions. I've read this on many news sites today.
So, if that actually turns out to be fact, and not just internet speak, there would have been such a huge police presence that people took notice and asked them what was up. And even with that huge presence, the person responsible for the bombings slipped in and achieved his objectives, at least partially. Either way, from the video I've seen alone, there was a lot of uniformed police, and who knows how many plainclothes units around.
Scary to consider, that with an area saturated with law enforcement, a person can STILL get in and create havoc. Like JFK said, all you have to do is be willing to trade your life for theirs, and anyone can kill him (the President). Well, apparently it goes further, and all you have to do is be able to build small bombs, and you can kill at will in a country with hugely impressive security system/police force/FBI/whatever, and even survive to do it again.
http://www.youtube.com/watch?feature=player_embedded&v=046MuD1pYJgAt risk of a ban over posting something, I want you to see that video. I was viewer number 124, now there is 9 million views a day later. It's not really a "NSFW" video, you can't really get a look at the hurt people thank god, but you do get a good look at the blast and the response right after it. Look at around 50 seconds after the blast, there is dozens of cops if you freeze frame and count, and even just after the initial blast, you can see one tall cop with his sidearm out, and about 4 o 5 others (top of their heads) within just seconds of the blast. I don't think anyone can fault the powers that be with having a lack of law enforcement in the vicinity. I just think that they weren't in an optimal location to prevent something like this - they were there mainly to protect the runners by the look of their deployment, not watch the crowd for possible terrorism.
I guess I have my perspective on this, having been in convoys hit almost daily for a long period of time, and having the building I slept in directly bombed twice. Securing against this type of thing is NOT easy. We had the Ghurka's protecting our building once, and you've never met meaner or more thorough guards anywhere, I guarantee it. Bombs still went off. Triple Canopy had Delta and Devgru living in their building in Iraq when the company first began ops inside Iraq. That building still got hit, with the best, the absolute VERY best in the world occupying and guarding it.
There is no defense, no absolute way to stop this, and that's the horror of it IMO. No amount of law enforcement, security, anything can prevent a determined attacker with an IQ over 100. Get a group of dedicated guys acting together...well, then you get Afghanistan/Iraq type situations, with this happening daily in multiple locations. I pray it doesn't happen over here.
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If that is the case and the bombs were made from conventional materials, the sweeps weren't often/thorough enough or the handlers weren't paying attention to the dogs.
As I said, they looked to be paying particular attention to the runners by my observation of how they were deployed. You are likely right - even with the huge dog presence, the bombs could have been missed by sloppy work/training, or they more likely were just dropped and then detonated quickly in order to exploit gaps in the security that whoever did this observed. As I've said, it really isn't all that hard to do, and if the best in the world can get hit, anybody can.