Global leaders gather in the Argentine capital for a G20 summit beginning tomorrow likely to be dominated by simmering international tensions over trade.

Here is a quick guide to what’s at stake for the main players.

US President Donald Trump, who has little interest in multilateral diplomacy, is coming to the Group of 20 summit for high-pressure talks with his counterparts in China and Russia.

Trump has cast his Buenos Aires meeting with Chinese President Xi Jinping as a deadline for Beijing to cave on key trade disputes or risk even further sanctions and pressure. The G20 will also mark Trump’s first substantive talks wth Russian President Vladimir Putin since a July summit in Helsinki, where the US leader’s deferential tone drew wide rebuke at home.

Trump has resisted once-routine global calls to fight protectionism and in June took the extraordinary step of refusing to sign a statement at a summit of the Group of Seven leading industrial democracies,

Chinese President Xi Jinping is expected to meet Trump to seek to break an impasse of their trade war on the sidelines of the G20 summit.

Xi has cast himself as a defender of globalization and opponent of protectionism, but US and European governments say foreign companies still face many hurdles to do business in the Communist-ruled country, including the forced transfer of technology or outright theft of intellectual property.

British Prime Minister Theresa May’s appearance is overshadowed by Brexit and in particular her attempt to convince lawmakers to ratify her agreement with the EU.

The crucial vote, which could also decide the fate of her premiership, is due to be held on December 11.

She is widely expected to lose the vote because of fierce opposition from Brexiteer lawmakers within her own Conservative Party, who say it makes too many concessions to Brussels, and pro-EU MPs who say it will devastate the British economy.

May became prime minister in July 2016 in the aftermath of the Brexit referendum and has clung to power despite losing her parliamentary majority in elections in 2017.

She wants post-Brexit Britain to take a leading role on the global stage as an independent trading nation but critics say her country’s

influence will wane outside of the EU.

Turkish President Recep Tayyip Erdogan will seek to use the summit to again project his image on the international stage as a champion of the poor and oppressed as well as an un-ignorable figure in international diplomacy.

The G20 is a crucial forum for Turkey as it seeks to build ties with key African and Latin American nations to assure its status as a global power.

Erdogan is also likely to press for justice on causes close to his heart such as the Palestinians or the Rohingya Muslims in Myanmar.

But the main focus could be on the murder of Saudi critic Jamal Khashoggi in Istanbul, with Saudi Crown Prince Mohammed bin Salman, at whom Turkish pro-government media have pointed the finger of blame over the killing, expected to also attend. Erdogan and the prince have not met face to face since the crisis erupted.

Argentina’s Prime Minister Mauricio Macri welcomes world leaders while his country has been brought its knees by an economic crisis which forced him to seek a massive International Monetary Fund bailout. Hit

by recession and 45 percent inflation, the center-right leader’s chances of building a strong challenge for a second term in next year’s elections look slim.

Deep public spending cuts have sparked a wave of strikes and street protests and Macri’s problems have been exacerbated by a falling peso and a dip in the price of soybeans, Argentina’s star export.