US President Donald Trump says he'll put heavy sanctions on Iraq after its president called for US troops to leave the country.
It comes after the US killed a top military general in neighbouring Iran.
A pro-Iran group of Iraqi MPs voted to call for US troops to leave Iraq - 5,000 of them are there as part of the international coalition against the Islamic State (IS) group.
But what are sanctions and how do they work?
What is a sanction?
Sanctions are punishments a country (or group of countries) puts on another country.
In this case, it would mean that the US bans American companies in certain industries from exporting their goods to Iraq.
US products sold in Iraq - which were worth £1.3bn in 2016 - include machinery, vehicles and medical instruments.
Sanctions can have serious consequences on the people living in Iraq - as they have in the past. More on that in a bit.
Why do countries use sanctions?
"You can impose sanctions against another state because you want to see a change in behaviour of the other state," says Professor Moritz Pieper, a lecturer in international relations at the University of Salford.
The idea is that "the population gets angry, and will demand from its own government to do something to rectify the situation."
Countries can also introduce sanctions in retaliation to other countries' sanctions.
For example, Russia did this in 2014 in response to restrictions put on them by the EU and USA.
What different types of sanctions are there?
The sanctions potentially being used by the USA are economic - they would ban companies from selling goods to Iraq.
Countries can also impose financial sanctions. That's when the financial assets of certain people or organisations are frozen, so they can't access their money in foreign bank accounts.
The US put financial sanctions on Russia in 2019 over the poisoning of a former Russian spy, Sergei Skripal, and his daughter Yulia in the UK.
US banks are now banned from providing loans to Russia.
When have sanctions been used against Iraq before?
The UN imposed strict economic sanctions against Iraq between 1990 and 2003.
This led to a humanitarian crisis in the 1990s as many Iraqis struggled to get hold of food and medicine.
The UN had to start a programme called oil-for-food, which exchanged food and other goods for Iraqi oil.
That programme was later caught up in a corruption scandal, where Iraq's leader Saddam Hussein was found to have made billions of dollars - and UN officials to have taken money from bribes - through the scheme.
What are 'smart sanctions'?
Sanctions can be quite a blunt instrument if they are a blanket ban on something, and can have unintended consequences.
But "smart sanctions" are sometimes used - they're much more targeted and designed to only punish a small number of people rather than an entire nation.
For example, people close to Syrian President Bashar al-Assad - including his wife Asma - have had their assets frozen over the government's violent response to the Syrian uprising.
What sanctions are the UK involved in?
The EU and the UN - which the UK is part of - often agree to sanction a certain country.
For example, there are bans on exporting arms to countries including Armenia, Iran and Syria.
The US and EU (including the UK) also enforced sanctions against Russia in 2014 as a result of the Russia-Ukraine conflict.
These "smart sanctions" targeted sectors managed by the powerful elite around Vladimir Putin, including banks and oil companies.
They also banned some of the major business leaders with ties to the Russian government from coming into the EU and US.
EU sanctions will no longer automatically take effect in the UK from the end of 2020 though, as long as Brexit is not postponed, according to sanctions lawyer Charles Enderby Smith.