Russian President Vladimir Putin will join dozens of world leaders at an online climate summit hosted by US President Joe Biden set to begin Thursday, despite a deep crisis in relations between the countries, the Kremlin said this week.

The White House summit, which will gather 40 presidents, prime ministers, environmental ministers and diplomats, is part of Biden’s effort to trumpet America’s return to the forefront of battling climate change after a four-year detour under his predecessor, Donald Trump.

Putin’s attendance signals he is still open to dialogue with the United States even though the two countries have imposed new sanctions on each other in the past few days. On Wednesday, Putin gave a national address warning of reprisals for foreign attempts to meddle in Russia’s affairs. He has yet to accept or decline an invitation from Biden to a separate bilateral summit.

The Kremlin said Putin’s address to the climate summit will “outline Russia’s approaches in the context of forging broad international cooperation aimed at overcoming the negative effects of global climate change.”

But it’s far from certain that Russia and other nations will follow suit if Biden pledges that the United States will endeavor to significantly cut emissions – reportedly by as much as 50 percent ­– making the summit a political and diplomatic risk.

The event, taking place on Earth Day, is also first time a global summit has been held virtually and livestreamed around the world, and it is difficult to predict what various world leaders, especially those who relish tweaking the United States, will say when given the opportunity.

Biden and his Special Envoy for Climate John Kerry have been working to push other major polluters like China, India, and members of the European Union to set similarly ambitious goals, many of which will be represented at the summit.

Biden has already rejoined the Paris climate agreement that Trump renounced and signed a raft of executive orders to reverse his predecessor’s environmental and climate decisions. But officials, activists and allies describe this week’s meeting of approximately 40 leaders as Biden’s first major effort beyond wiping away Trump’s policies.

“The president wanted to convene this summit early in his presidency to ensure close coordination with key players in the international community and at the highest levels of government,” said White House press secretary Jen Psaki. “Obviously, the United States is one of the world’s largest emitters, but so are a number of countries who will be represented.”

Over the past day, Kerry has announced measures that will help the United States reduce its share of global emissions including tackling emissions from shipping and a partnership with financial firms.

Activists, some corporations and other world leaders want an aggressive U.S. target, and some reacted early to say the reported 50 percent cut would not be sufficient.

“While many will applaud the president’s commitment to cut U.S. emissions by at least half by 2030, we have a responsibility to tell the truth: it is nowhere near enough,” Evan Weber, political director of influential youth activists group the Sunrise Movement, told Reuters, adding that reported pledge “will be a death sentence for our generation and the billions of people at the frontlines of the climate crisis in the US and abroad.”