As we know the war in Iraq is brutal "slaughter" , most media outlets are showing there should be some sort of intervention to stop the needless deaths , but how many fronts are there that the U.S. is involved in .
The U.S. is big , but is committing resources in a spread out fashion , they need to be careful not to spread themselves too thin to maintain impact and "influential knowledge" of their strength , especially with problems arising in Ukraine .
On one hand they want a tough stance in Eastern Ukraine , though at same time are dealing with "humanity" issues in Middle East , perhaps Russia has noticed this 'chess board game' and knows U.S. will not directly intervene in Ukraine when dealing with Iraq , Syria and Israel even be it to limited extent . They simply can not afford to space their influence too weakly or may also start to effect how the U.S. is perceived , hence creating the possibilities of further opposing forces, or even further current problems [a balance needs to be maintained] ; people/groups that wait for a chance to strike against U.S. when they are at their weakest and weakest influentially in some forms .
Another possibility is heightening of public reaction , I think the U.S. is obligated to get involved when the humanitarian crisis in Iraq gets to an actual noticeable point of terror , though video/vision is limited of the war and not at a level that displays the impact , and the impact being a noticeable level 'in particular' , hence diminishing impact ; with public's own media/social forms [normalisation] .
Obama has said though there will be no military injunction in Iraq , I suppose he wants other countries to take some of the brunt of public outcry against the war, instead of just the U.S. .
The U.S. has a problem with dealing with war efforts , Americans are sick of war , hence he may of withdrawn troops from Iraq for that reason [he needs to maintain a political/public majority] , quite a few were speaking against being involved in other countries issues [war] , now suddenly the media is "heightening" the controversial issue that 'innocence is about to be taken , civilians trapped on a mountain for example .
This is war , it is all about how you are perceived to your enemy [show strength] , also about having mass impact that will not effect your other objectives , public reactions (U.S. citizens/politicians] with it's own citizens having influence of compassion towards the displaced in Iraq, though media controls this to certain extent , in effect , effecting war efforts .
I believe Obama is restricting his efforts in Iraq to see or wait for level of public outcry [judging the level], in effect also influencing people to fight for the humanitarian cause in Iraq , a time of less debate "against" striking in Iraq , he possibly needs to as well . As you may be aware strategists sit round considering all avenues and angles , its simply part of defence/security .
Obama has to use his influence to impact' Iraq into saving their own people , as the need to attack positions on front for example and devote troops to actually saving the Iraq people are possibly conflicting . Iraq would be left deciding in this case to devote critical resources towards saving civilians , in a false hope that U.S. military will help to a further extent when needed , appearing at least to please west ideals to gain 'possibility' of support needs .
Though as someone like myself who is against violence , I believe the U. S. needs to so called "invade" to stop the slaughter against these civilians who are simply running for their lives in "fright/fear states" - its simply not a way to expect people to live and therefore intervention is needed .