Spoilers ahead! Please be warned!
As far as I understand, it is implied the New Republic does not see the First Order as a serious threat. And because of this the First Order is able to strike and destroy the planets of the Hosnian System including the Republic's capital.
That just does not make much sense to me. And here is why.
The Starkiller Base is a project of an enormous scale. It is apparently much bigger -- or at least powerful -- than the original Death Star. So a huge number of personnel has to be involved into building something like the Starkiller Base. Plus, the project would require a gigantic amount of resources to complete.
So, assuming the number of personnel involved, how is it even possible to keep the Starkiller a secret from the Republic? It seems logical to assume the Republic has some kind of intelligence service that could find out about a project of that scale or even maybe infiltrate an agent there.
Secondly, the First Order possessing the amount of resources necessary to build the Starkiller -- how is it possible the Republic does not perceive the First Order as a major threat in the first place? The civil war of the Republic and the Empire has apparently just ended. You would expect the Republic to consider basically the Empire's successor as a big danger.
Does anyone have an in-universe explanation of the things mentioned above?
Most in the New Republic ignore the growing menace of the First Order, but not Leia - after all, the Organas have a history of seeing bad shit coming down the pike. She pleads with the New Republic to deal with the FIrst Order, but everybody thinks she's overreacting; finally she's able to convince the powers-that-be to let her go off and lead a small resistance group which she then imaginatively names The Resistance.– phantom42 Dec 23 '15 at 15:26