It is time to officially recognize Jerusalem as the capital of Israel."

He reversed decades of consensus about the status of Jerusalem.

The announcement sparked massive protests among Palestinians and throughout the Muslim world.

Here are five things to know about Jerusalem and why it's so contentious.

Israel has controlled West Jerusalem since 1949.

During the Six-Day War Israel captured East Jerusalem and annexed that half of the city,

but the international community considers East Jerusalem occupied territory.

In 1980 after Israel passed a law declaring a united Jerusalem their capital,

the United Nations condemned the annexation. Palestinians want to divide the city and

make East Jerusalem the capital of a future Palestinian state,

while Israel iswant a unified Jerusalem to be their capital.

During peace process negotiations for the Oslo Accords, the issue of Jerusalem was initially set aside to avoid derailing the talks.

In 2000, during a new round of negotiations, talks were upended

when the leaders of Palestine and Israel disputed who would control the maze of tunnels under Jerusalem.

Control of Jerusalem has been a trigger for violence many times in the past.

The contested area of East Jerusalem is home to some of the holiest sites in the world for Jews and Muslims.

It is the site where Judaism's two sacred temples once stood and the site

where the Prophet Mohammed ascended to heaven.

The trouble is that the sites for Muslims and Jews exist on the same land.

There's a precarious power share in place:

Israeli officials control who has access to the complex, but Muslims have religious control inside.

Jews can enter but, aren't allowed to pray. Instead, they use the Western Wall.

The Second Intifada began in 2000 when then-opposition leader Ariel Sharon

visited the Temple Mount, to assert Israel's right to the complex.

Palestinians protested and were met with tear gas and rubber bullets.

The violence lasted five years and killed over 3,000 Palestinians and

nearly 1,000 Israelis, with thousands more wounded.

More recently, Israel set up metal detectors to enter the complex,

which Palestinians say restricted access to the holy site, sparking a new round of protests and violence.

In the early '70s sixteen countries had embassies including the Netherlands, Costa Rica, Colombia,

but after the UN Security Council condemned the annexation of East Jerusalem in 1980,

member states left. Now Jerusalem only has consulates -

the U.S. would be the first country to have an embassy back in the city.

Though Congress passed a law to relocate the U.S. embassy to Jerusalem more than 20 years ago,

the law includes a loophole that allows the president to delay the relocation for the sake of national security.

Every sitting president, Clinton, Bush, Obama,

has used this power and signed the waiver every six months.

President Trump signed the waiver in June 2017 and again in December 2017,

but also signaled he would begin the process of moving the embassy from Tel Aviv to Jerusalem.

President Trump was careful not to call Jerusalem the undivided capital of Israel,

but opposition to Trump's declarations and the proposed embassy move grows.

Muslim countries worldwide urge the recognition of East Jerusalem

as the capital of a future Palestinian state.

In Jerusalem, tensions are higher than usual.

Palestinian militant group Hamas has started launching rockets into

Israel from Gaza and calling for a third Intifada.

Israel has arrested Palestinians and is clamping down on protests and

as lines are drawn and the fight for Jerusalem intensifies,

the future of israeli-palestinian stability is once again at risk.