How to invite the US to invade your country: few easy steps

Well, this is not really a guide to "how to invite the US to invade your country" as it is a guide to How the US manages to give you the method in which you may invite the US to invade your country.  The US sets a threshold beyond which the situation can't be tolerable: you speak of "red lines" and of "game changer" and you allow those who are eager to invite you to invade because they want you to install them into power to present you "evidence"--real or manufactured--to facilitate the invasion.  We told the world that Iraqi WMDs are the pretext, and Ahmad Chalabi (Iranian regime's man in Iraq these days) produced "curveball" who dutifully had visions of mobile labs and of various WMDs in the country.  For Syria, Obama said that chemical weapon use would be the pretext for war.  Now the notion that the armed Syrian opposition would produce evidence is never considered by US media, especially that the Times of London among other media AND governments (like Israel) speak about evidence based upon pictures or videos posted by the opposition on the internet.  As to why the Syrian regime, which has a ton of arsenal of conventional weapons to kill would need to resort to chemical weapon use "for limited use--mind you", can't be logically explained and maybe one of those things that St. Augustine would defer to divine wisdom to explain.  This is like last week, Syrian opposition claimed that Syrian regime dropped chemical weapons on a neighborhood in Aleppo and killed three people--KID YOU NOT.  Would not conventional weapon in this case be more effective?