A jetliner flies over the G20 summit venue at the Costa Salguero Center in Buenos Aires, Argentina, Nov. 28, 2018.
A jetliner flies over the G20 summit venue at the Costa Salguero Center in Buenos Aires, Argentina, Nov. 28, 2018.

LONDON - World leaders are preparing for what’s set to be a fiery G-20 summit starting Friday in Buenos Aires.  The two-day meeting brings together leaders representing two-thirds of the world's people and 85 percent of the global economy.

The summit is being held against the backdrop of a spiraling trade war between the United States and China that has set the global economy on edge, on top of a series of geopolitical flashpoints from Ukraine, to the Middle East, to the South China Sea.


WATCH: G-20 Prepares for Fiery Summit Amid Trade War, Security Tensions

U.S. President Donald Trump has threatened to raise existing tariffs from 10 percent to 25 percent on $200 billion worth of Chinese imports and has warned of more penalties if no agreement is reached with Beijing on issues like trade imbalances and intellectual property.

The White House believes it holds the momentum for a possible deal.

"Most observers believe China to be in a slump whereas the United States is in a very strong, solid position going into this summit,” White House Economic Adviser Larry Kudlow said Tuesday.

Shoppers sit on a bench with a decorated U.S. flag
FILE - Shoppers sit on a bench decorated with a U.S. flag browsing their smartphones outside a boutique selling U.S. brand clothing in a shopping mall in Beijing, China, Sept. 24, 2018.

China’s ambassador to the United States, Cui Tiankai, warned of grave consequences if the trade war intensifies.

"In the last century we had two world wars, and in between them a Great Depression. I don't think anyone should really try to have a repetition of history,” Tiankai said Wednesday.

The first G-20 leaders’ summit was held in the wake of the global financial crisis in 2008.  Since then there has been a role reversal says Tristen Naylor, professor of international relations at the London School of Economics.

“A decade on, the greatest threat to established economic order is actually surprisingly coming from in many ways the chief defender of that order, with the protectionist trade wars kicked off by President Trump and the ‘America First’ foreign policy.”

Geopolitical tensions between several G-20 nations are simmering. The meeting comes days after Russia rammed Ukrainian vessels in international waters off Crimea and seized several of its naval personnel. Kyiv has warned that it faces the danger of an all-out war with its neighbor.

Russian fighter jets fly over vessels after the ch
FILE - Russian fighter jets fly over vessels in the Black Sea off Crimea as part of operations to stop three Ukrainian navy ships from entering the Sea of Azov, Nov. 25, 2018.

In response, Trump raised doubts about a planned meeting at the summit with his Russian counterpart, Vladimir Putin, telling The Washington Post newspaper that he was "awaiting a full report from his national security team about the incident."

He then abruptly canceled the meeting after a in-flight briefing on his way to Buenos Aires.  

Speaking Wednesday to business leaders in Moscow, President Putin blamed Ukraine.

“What was the [Russian] border control force supposed to do?  Military ships have illegally entered into the territorial waters of the Russian Federation,” Putin said.

Also scheduled to attend the summit is Saudi Arabia’s crown prince, Mohammed bin Salman, who the West has implicated in the torture and killing last month of journalist Jamal Khashoggi in Istanbul. Turkey’s president, Recep Tayyip Erdogan, will also be there.

“All are going to be in the same room at the same time.  And this is a critical moment for them to at least discuss some of the critical flashpoints,” says analyst Naylor.

FILE - A man holds a poster of Saudi Crown Prince
FILE - A man holds a poster showing images of Saudi Crown Prince Muhammed bin Salman (L), dubbed "assassin," and of journalist writer Jamal Khashoggi, dubbed "martyr," during a prayer service for Khashoggi, in Istanbul, Turkey, Nov. 16, 2018.

He adds that it’s vital the summit is seen to make progress on key global challenges.

“How ought the economic system operate? Is protectionism a good thing or a bad thing? Is climate change real or not? If these countries can’t agree, it sends a very, very strong signal to everybody not at the table that maybe they don’t need to sign up.”

Thousands of anti-globalization protesters are gathering in Buenos Aires.  Many Argentineans are angry at the government’s $57 billion rescue package with the International Monetary Fund, in return for sweeping spending cuts.

About 22,000 police officers are being deployed in Argentina's capital, but some of the fiercest battles could take place inside the summit itself.