Much will depend on Iran’s response to what it sees as Israeli and US provocation, including the November assassination of an Iranian nuclear scientist.
Iraq has asked the US to start withdrawing troops. If it doesn't, that's a breach of international law.
Sending specially trained operatives into hostile territories dates back to Colonial days. In the past decade, special operations forces have become central to America’s counterterrorism efforts.
Despite apparent unity after the killing of an Iranian general by the U.S., deep divisions still mark the Middle Eastern country.
Some of the major events in US-Iran relations highlight the differences between the nations' views, but others presented real opportunities for reconciliation.
Iraqis have taken to the streets to protest against the foreign interference – by both Iran and the US – in their country.
Since President Donald Trump took office, Iranians have held a more unfavorable view of the US.
In recent decades, most nations have agreed on certain norms to ensure peace, including an end to assassinations. Trump's move to kill an Iranian general upends this carefully balanced system.
The history of the Iran-United States relationship is complex and often brutal. Understanding it helps put today's turmoil into sharper focus.
The downing of Flight PS752 isn't just the result of Canada being caught in U.S.-Iran crossfire. It's also the result of an unnecessarily aggressive posture of Canada's own against Iran in 2012.
Flight PS752 is more than just a terrible tragedy. It's also revealed the potential future costs of Iran's irresponsibility.
Iranian leaders seem eager to use the powerful emotions surrounding his death to coalesce power around the regime. History shows that mass mourning is a powerful way to bring people together.
'Zulm,' an Arabic word meaning extreme injustice, could explain why Iran appears to be so united in anger at the US killing of Gen. Qassam Soleimani.
After the assassination of General Qassem Soleimani, further esclation in the conflict between Iran and the US could come in the form of a cyber-attack.
Both President Trump and President Obama used military force without informing Congress, or getting its approval. But the differences reveal more than the similarities.
The US and other countries set up the modern system of international law after World War II. Does the US killing of an Iranian general violate those laws? What about Iran's attack on US bases in Iraq?
Even when countries have broken ties with each other, they can communicate – as the US and Iran did just a few days ago.
Although neither side apparently wants conflict, tensions remain over the presence of US troops in Iraq and Iran's decision to walk away from part of the 2015 nuclear deal.
President Trump's speech about Iran wasn't just aimed at that country or the US. He also targeted NATO allies, urging members of the alliance to step up and help US efforts in the Middle East.
Iran's missile strikes on Iraqi bases in response to the killing of Iranian general Qassem Soleimani have raised tensions between the U.S. and Iran. But war seems unlikely at this point.