Like Afghanistan 10 years down the line those supporting this action will be damning the toll it takes, US sadly still operates in the same manner of a gone era to uphold its interests but the world has long since changed that makes this harder for them ironically due to their own actions, the Iraq fiasco put countries on alert as it highlighted the nation would go through with an illegal unsubstantiated war hence why the likes of North Korea armed themselves with nukes, the weaponizing of the dollar has lead to countries developing their own pipeline for trade to drop the currency's use so they don't need to worry about sanctions if they don't follow the US' political stances it has also boosted China as many countries are instead using them for investment, the intervention in helping remove Ghaddafi in Libya leaving the country as a failed stated was seen as a move to stop a new rival trading currency, the Turkish battle with Kurds highlights if the is no gain from you US don't care despite what ever pledge they've previously made etc...

Iran for anyone unaware control a region where shipped oil has to pass through they have the power to stifle oil supply this was one factor in the 1950's debacle which is now coming back full circle and why the is a lot of political interest thrown at them the whole Shi'a/Sunni battle is a political diversion in why they have an issue with the country, Iran are not easy opponents either like the Afghans everyone who has gone in there has been mullered. This move seems like a kneejerk reaction to the ever changing balance of power that has been altered to make the world even harder to bend to their interests especially with China, Russia and Iran getting along.

My biggest worry is that I haven't seen any indication that any of our allies stand by this assassination. It seems like a strictly unilateral decision regarding something which very well might have global repercussions. If the US does fall into a war here, we might be going in alone...

Odds are this will have close to zero consequences.

Trump has been very open in his contempt for the international community as a whole, allies included, and has worked publically towards 'putting America first' no matter the toes stepped on in the process.

American international relations are not what they used to be and when combined with such inflammatory and provocative actions I would expect to see a widespread trepidation towards this most recent escalation towards a major conflict. 

It is no longer in the best interests of the larger international community to become haphazardly embroiled in potential dispute, especially considering warming relations among other major global players. 

Hence the gravity of this entire situation. 

When it comes to politics, I'm not the most informed. I do appreciate this forum and the diversity of its members. It gives me a pretty good idea what the rest of the world thinks of my country and our actions. I often read posts here (ignoring a few) and end up with a better idea.

Someone has already given some reasoning but to add to it Europe has a lot on its plate right now with the EU situation as well as economical issues and Iran is not an easy fight for reference look at how their military power compares to us in the UK below (taken form the express a media outlet in the UK just over a week ago).

This is a strong stable establishment that also has sizable military power, control over an area where all oil has to pass through to be shipped to other nations while having their own huge reserves of oil which has been further boosted by a new oil find and have support from both Russia and China. Only nation supporting this is Israel which no surprise given them and Iran haven't got on for decades.

The consequences for this are already happening, we may yet avoid major conflict, but the toll of the politics 'behind closed doors' will be felt globally. From fuel prices and taxes to the shifting of political alliances and global direction, however large or small.

War is not the only consequence here, nor is it mutually exclusive. 

Congress has been useless when it comes to keeping presidents in checks. Bush, Obama and now Trump have turned the entire world into a battlefield using drones outside the context of armed conflicts, which violates international law. One can argue that drone attacks have been worse than armed conflicts due to the shocking disregard for civilians and the fact that they take place outside of war zones. Lack of congressional engagement has become the norm when it comes to acts of war. 

Can you guys hear that? It's the US sounding the drum of war once again. I'm sick and tired of hearing that sound. I've heard it all throughout my life and so have my parents and their parents and their parents. The war mongering military and intelligence at it once again