Andre: I don't want to sound glib about it, but normally, reproducing a material part of a work without authorization under US law is copyright infringement, even if the usage is not done for profit. That is true even if the copied material is not further disseminated to the public, i.e. so-called 'private copying,' an issue which came up repeatedly in the early 'file sharing' cases, and which used to arise in photocopying cases as well, particularly in academic and institutional settings. The issue also comes up in the so-called interim copying cases, where someone will sample or mix material into a recording but manipulate it to such an extent that the end product is virtually unrecognizable. There, the copying occurs in an internal layer of production, but not in the end product. That's not the issue here, though, which would involve both copying and dissemination, either in the form of the distribution of copies or their public display, implicating two or three of the exclusive rights of the copyright owner.
As to the specific provisions of US law, it is largely addressed by section 106, which provides for the exclusive rights of the author: reproduction, adaption, distribution, public performance and display. Section 107 contains a barebones recitation of the so-called 'fair use' factors, which take into account the purpose of the secondary use (the copying activity), the nature of the copyrighted work (e.g. fact or fiction), the amount of material taken relative to the original work in its entirety, and the potential harm to the market for the original work should the unauthorized copying be widespread. Reposting the article would not qualify under these factors, and there is quite a bit of case law discussing their application in different fact settings. (Interestingly, the factors were in existence long before they were codified in the 1976 Act, and were articulated by Justice Story in 1840 in a case involving the unauthorized publication of letters of George Washington, in a case called Folsom v. Marsh). Posting a link to an authorized Internet publication is generally considered OK because you are not 'copying' but redirecting the browser to the site where the original appears (assuming that it is authorized in the first place, and not itself an infringement). But that's not the issue here. The law in other countries, while different in some ways, typically comes out to the same result. There are also some statutory exemptions which aren't applicable here, so we need not delve into those in detail now.
Professor hat off.
And apologies if this sounds like pontification. But you asked.