U.S. President Donald Trump arrived for G20 summit in Hamburg on Thursday facing a difference audience after departing Poland on a high note.

Trump, who paused to wave as he descended the steps of Air Force One with his wife Melania, would be facing off with leaders of the other big G20 economies after deciding last month to pull the U.S.out of the 2015 Paris climate deal.

Trade policy is another area of contention at the summit, which protesters vowed to disrupt.

“Welcome to Hell’’ was their greeting for world leaders arriving in Hamburg for the two-day meeting which would formally start on Friday.

German Chancellor, Angela Merkel, hosting the meeting, said she was committed to open international trading system, in spite of anxieties about U.S. protectionism under the Trump administration.

“We are united in our will to strengthen multilateral relations at the G20 summit. We need an open society, especially open trade flows,” Merkel, who is running for a fourth term in a September election, said in Berlin.

There were options for finding a solution on climate, she said on her arrival in Hamburg, adding that as the summit’s host she would work to find avenues for compromise.

She and Trump were due to meet on Thursday evening before the leaders begin the full summit on Friday to discuss a raft of issues ranging from climate and trade to migration, support for Africa, and fighting terrorism.

Turkey’s Tayyip Erdogan is among other leaders Merkel will meet.

Trump, who earlier in Poland called again on NATO partners to spend more on defence and said he would confront the threat from North Korea, is also due to hold his first face-to-face meeting with Russian President Vladimir Putin on the sidelines of the summit.

Their meeting, scheduled for Friday, will be closely watched at a time when mutual ties remain strained by allegations of Russian election interference, the war in Syria and Ukraine

Ahead of the meeting, Putin threw his weight behind the Paris accord.

“We see the Paris Agreement as a secure basis for long-term climate regulation founded on international law and we want to make a comprehensive contribution to its implementation,” he told German business daily Handelsblatt.

Thousands of protesters from around Europe poured into Hamburg to join the main demonstration, dubbed “Welcome to Hell” by the alliance of anti-capitalist groups who organised it.

Police expected around 100,000 protesters in the port city, some 8,000 of whom are deemed by security forces to be ready to commit violence.

Up to 20,000 police officers will be on hand for the main demonstration.

(Source: Reuters/NAN/Sun News Online)