Most U.S. tariffs on China will remain in place during phase 2 trade negotiations, U.S. President Donald Trump said on Tuesday while addressing the 2020 World Economic Forum in Davos, Switzerland. 

"Our relationship with China right now has probably never been better. We went through a very rough patch, but it's never ever been better," Trump said, adding his relationship with Chinese President Xi Jinping is an "extraordinary one."  

Hailing that the newly signed trade deals with China and Mexico represent "a new model of trade for the 21st century," Trump touted his administration's achievements since he took office three years ago.

"The time for skepticism is over," Trump said, suggesting that he rescued the U.S. economy, stating that, "America is winning like never before." 

The address was pitched to appeal to the Davos crowd as his impeachment trial begins in earnest in the U.S. Senate after the Republican president was formally charged by the Democratic-controlled House of Representatives in December with "high crimes and misdemeanors."

Trump calls impeachment trial a long-running 'hoax'

Trump, who is expected to be acquitted by the Republican-controlled Senate, repeatedly called the impeachment trial set to reconvene later Tuesday in Washington a "hoax" shortly before touting his economic achievements in his Davos speech.

"It's a witch hunt that's been going on for years and it's frankly, it's disgraceful," the U.S. president told reporters as he headed into the packed conference hall to give his remarks.

"That whole thing is a total hoax so I'm sure it is going to work out fine," he reiterated after his speech.

Greta says planting not enough after Trump backs trillion tree plan

Climate activist Greta Thunberg, also speaking at this year's Davos, blasted world leaders' climate inaction in an apparent rebuke to a planting pledge made by U.S. President Trump in his speech.

Trump announced the U.S. would join an existing initiative to plant 1 trillion trees, but also spoke at length about the economic importance of oil and gas and called climate change activists "pessimistic" and the "heirs of yesterday's foolish fortune tellers".

When questioned by reporters on his environmental and climate policies, Trump said "I'm a very big believer in the environment".

"We right now are doing extremely well in the United States, but what I want is the cleanest water, the cleanest air and that's what we're going to have, and that's what we have right now."

Thunberg responded by referring to "empty words and promises" by world leaders, saying that "our house is still on fire" and that planting trees was not enough to address climate change. 

Having taken the U.S. out of the landmark 2015 Paris accord to fight climate change, Trump's administration has called for expanded use of carbon-spewing coal, stripped away environmental protections and played down concerns among scientists about man-made climate change.