War may or may not have changed significantly (it depends on which aspect, really) but it still does have striking similarities compared to what it was a hundred years ago. A striking similarity to the still on-going Iraq War (which has become an insurgency) is the Spanish-American War. The factuality of the casus belli for both wars were questioned only after the war was ended. For example, the casus belli for the Spanish-American War, the sinking of the USS Maine, is today leaning to the side of the investigation that it was a false flag operation of the US (staged, that is) designed specifically to swing the favor of the American politicians and the public in going to war. Whether this was true or not is not the case as yellow journalism was what largely gave the US the push with newspaper headlines that served as the judge, jury, and the executioner against Spain (“Destruction of the warship Maine was caused by the enemy”).
This is not much different from how the Iraq war was started. A series of reports and investigations of both malicious and realistic outcomes were shared among what would be some of the members of the Coalition Provisional Authority. Naji Sabri, then Iraqi foreign minister who was being paid as an agent, allegedly reported that there were no WMDs in Iraq but that Bush decided to dismiss the information. It further worsened the situation when other Iraqi sources started showing up and later admitted to lying to their European contacts that the regime had WMDs. As it was with the Spanish-American War, the US opened conflicts with Iraq despite the presence of unclear and maligned information. War, like it was nearly a hundred years ago, was all about satisfying the desires of a state, even if it infringes the rights of another. Who’s willing to go that far differs from country to country (like how China states over and over that it wishes to resolve the tensions peacefully in the South China Sea.