1700 arrests - means nothing.
OK, a little OT, but it needs to be said,
The number of arrests that a programme produces is irrelevant. Being arrested is not an indication that a person is a criminal, or even that they've done anything wrong. For that to be the case, you have to be charged with something, and then FOUND GUILTY. All it means to be arrested at an airport is that some over-zealous oik has taken a dislike to you and you've missed your flight.
Similarly with all the powers, resources, time, money, experts, surveillance and forensics available to them, the governments record on actually finding terrorists, charging them and gaining convictions is so low as to constitute harassment - somewhere around 2% of people arrested for terrorism related offences are actually charged (and then usually for some unrelated offence, such as searches of their house/computer, revealing smut or drugs crimes) and even fewer convicted.
However, big numbers sound impressive - and give the false illusion that progress is being made. What would be nice, but will never happen, is for some enterprising journo to take a step back, stop passively regurgitating government figures, and ask some probing questions such as "that's all very well minister, but how many actual convictions have been made?" We can only hope ...