Donald Trump's decision to recognise Jerusalem as the capital of Israel was met with fierce condemnation from leaders around the world.
Here are some key questions to explain the dispute.
Why is it a contentious issue?
The status of Jerusalem has long been a sensitive issue in the Israeli-Palestinian conflict, and is considered disputed territory by many countries.
Both Israel and Palestine claim Jerusalem as their capital, but neither is internationally recognised.
In 1980, Israel passed a law declaring Jerusalem to be Israel's "complete and united" capital, but the United Nations Security Council condemned this and passed a resolution that it would not recognise the law.
Palestinians, meanwhile, see east Jerusalem, which Israel captured in 1967, as their capital and view Mr Trump's move as a decision to side with Israel.
Have any countries ever had their embassies in Jerusalem?
A number of countries used to have their embassies in Jerusalem, but this changed after the UN Security Council resolution in 1980.
Costa Rica and El Salvador were the last to move their embassies out of the holy city in 2006, joining all other embassies in Tel Aviv.
Some countries do maintain consulates in Jerusalem, however.
Why has Mr Trump decided to recognise Jerusalem as Israel's capital?
The US President said he believed the decision to be "in America's interests", and marked a "new approach" to the conflict between Israel and the Palestinians.
Mr Trump said he was not delivering any verdict about where an Israeli-Palestinian border should lie, but said he was recognising the reality that most of Israel's government already operates from the city.
What has the international reaction been?
Leaders across the world have condemned Mr Trump for recognising Jerusalem as Israel's capital, over fears it could worsen tensions in the volatile Middle East.
Prime Minister Theresa May said she disagrees with the president's decision and reiterated Britain's position that the city should be the shared capital of Israel and Palestine in a negotiated two-state solution.
Labour leader Jeremy Corbyn described Mr Trump's move as "reckless".
Palestinian leader Mahmoud Abbas said the decision by the US President was "a declaration of withdrawal from the role it has played in the peace process".
But Israel's Prime Minister Benjamin Netanyahu welcomed the decision, calling it an "important step towards peace".
What will happen next?
Mr Trump has already announced plans to move the US embassy in Israel from Tel Aviv to the holy city.
But in the short-term, there are fears that the decision could spark violent protests, with US personnel and their families ordered to avoid visiting Jerusalem's Old City or the West Bank.
US embassies and consulates around the world have also been put on high alert.