Swedish climate activist Greta Thunberg attends the Youth4Climate pre-COP26 conference in Milan, Italy, September 28, 2021. REUTERS/Flavio Lo Scalzo

Swedish climate activist Greta Thunberg attends the Youth4Climate pre-COP26 conference in Milan, Italy, September 28, 2021. REUTERS/Flavio Lo Scalzo

Greek Defence Minister Nikolaos Panagiotopoulos, Greek Foreign Affairs Minister Nikos Dendias, French Foreign Affairs Minister Jean-Yves Le Drian and French Defence Minister Florence Parly take part in the signing ceremony of a new defence deal at The Elysee Palace in Paris, France September 28, 2021. Ludovic Marin/Pool via REUTERS

Kevin Kuehnert, one of the vice-leaders of Germany's SPD party, throws a face mask into a dustbin as he arrives for a meeting with his party's parliamentary group in Berlin, Germany, September 28, 2021. Tobias Schwarz/Pool via REUTERS

Kevin Kuehnert, one of the vice-leaders of Germany's SPD party, arrives for a meeting with the party's parliamentary group in Berlin, Germany, September 28, 2021. Tobias Schwarz/Pool via REUTERS

German Finance Minister, Vice-Chancellor and SPD party's candidate for chancellor Olaf Scholz, SPD's parliamentary group leader Rolf Muetzenich, SPD's parliamentary manager Carsten Schneider and SPD's co-leader Norbert Walter-Borjans arrive for a meeting with the party's parliamentary group in Berlin, Germany, September 28, 2021. Tobias Schwarz/Pool via REUTERS

Greek Prime Minister Kyriakos Mitsotakis speaks as French President Emmanuel Macron listens on during a signing ceremony of a new defence deal at The Elysee Palace in Paris, France September 28, 2021. Ludovic Marin/Pool via REUTERS

A Twin-Tailed Scorpion drone takes part in the China International Aviation and Aerospace Exhibition, or Airshow China, in Zhuhai, Guangdong province, China September 28, 2021. REUTERS/Aly Song

French President Emmanuel Macron gives a press conference with Greek Prime Minister during a signing ceremony of a new defence deal at The Elysee Palace in Paris, France September 28, 2021. Ludovic Marin/Pool via REUTERS

French President Emmanuel Macron gives a press conference with Greek Prime Minister during a signing ceremony of a new defence deal at The Elysee Palace in Paris, France September 28, 2021. Ludovic Marin/Pool via REUTERS

A Twin-Tailed Scorpion drone takes part in the China International Aviation and Aerospace Exhibition, or Airshow China, in Zhuhai, Guangdong province, China September 28, 2021. REUTERS/Aly Song

French President Emmanuel Macron gives a press conference with Greek Prime Minister during a signing ceremony of a new defence deal at The Elysee Palace in Paris, France September 28, 2021. Ludovic Marin/Pool via REUTERS

Vehicles of the military emergency unit are seen on a mountain surrounded by a cloud following the eruption of a volcano on the Canary Island of La Palma, in Todoque, Spain, September 28, 2021. REUTERS/Nacho Doce

People walk past the booth of State Administration of Science, Technology and Industry for National Defence at the China International Aviation and Aerospace Exhibition, or Airshow China, in Zhuhai, Guangdong province, China September 28, 2021. REUTERS/Aly Song

A model of Airbus A350-1000 jetliner is displayed at the China International Aviation and Aerospace Exhibition, or Airshow China, in Zhuhai, Guangdong province, China September 28, 2021. REUTERS/Aly Song

Greek Prime Minister Kyriakos Mitsotakis shakes hands with French Foreign Affairs Minister Jean-Yves Le Drian as French President Emmanuel Macron shakes hands with French Defence Minister Florence Parly next to Greek Foreign Affairs Minister Nikos Dendias during the signing ceremony of a new defence deal at The Elysee Palace in Paris, France September 28, 2021. Ludovic Marin/Pool via REUTERS

A model of Boeing 777 airliner is seen displayed at the China International Aviation and Aerospace Exhibition, or Airshow China, in Zhuhai, Guangdong province, China September 28, 2021. REUTERS/Aly Song

Germany's SPD party parliamentary group leader Rolf Muetzenich addresses the media before a meeting of the group in Berlin, Germany, September 28, 2021. Tobias Schwarz/Pool via REUTERS

German Finance Minister, Vice-Chancellor and SPD party's candidate for chancellor Olaf Scholz arrives for a meeting with his party's parliamentary group in Berlin, Germany, September 28, 2021. Tobias Schwarz/Pool via REUTERS

Germany's SPD party parliamentary group leader Rolf Muetzenich addresses the media before a meeting of the group in Berlin, Germany, September 28, 2021. Tobias Schwarz/Pool via REUTERS

German Finance Minister, Vice-Chancellor and SPD party's candidate for chancellor Olaf Scholz arrives for a meeting with his party's parliamentary group in Berlin, Germany, September 28, 2021. Tobias Schwarz/Pool via REUTERS

German Finance Minister, Vice-Chancellor and SPD party's candidate for chancellor Olaf Scholz and SPD's parliamentary group leader Rolf Muetzenich arrive for a meeting with the party's parliamentary group in Berlin, Germany, September 28, 2021. Tobias Schwarz/Pool via REUTERS

Greek Defence Minister Nikolaos Panagiotopoulos, Greek Foreign Affairs Minister Nikos Dendias, French Foreign Affairs Minister Jean-Yves Le Drian and French Defence Minister Florence Parly look at a pen during the signing ceremony of a new defence deal at The Elysee Palace in Paris, France September 28, 2021. Ludovic Marin/Pool via REUTERS

Germany's SPD party parliamentary group leader Rolf Muetzenich addresses the media before a meeting of the group in Berlin, Germany, September 28, 2021. Tobias Schwarz/Pool via REUTERS

A woman walks past a Boeing logo at the China International Aviation and Aerospace Exhibition, or Airshow China, in Zhuhai, Guangdong province, China September 28, 2021. REUTERS/Aly Song

French President Emmanuel Macron speaks during a press conference with Greek Prime Minister during a signing ceremony of a new defence deal at The Elysee Palace in Paris, France September 28, 2021. Ludovic Marin/Pool via REUTERS

Visitors stand near a model of WJ-700 armed reconnaissance drone displayed at the China International Aviation and Aerospace Exhibition, or Airshow China, in Zhuhai, Guangdong province, China September 28, 2021. REUTERS/Aly Song

A woman walks past a floral installation set up ahead of the China's National Day, which marks the 72nd anniversary of the founding of People's Republic of China, in Beijing, China September 28, 2021. REUTERS/Tingshu Wang

People take photos in front of a floral installation with the theme of space exploration, ahead of the China's National Day, which marks the 72nd anniversary of the founding of People's Republic of China, in Beijing, China September 28, 2021. REUTERS/Tingshu Wang

French President Emmanuel Macron speaks during a press conference with Greek Prime Minister during a signing ceremony of a new defence deal at The Elysee Palace in Paris, France September 28, 2021. Ludovic Marin/Pool via REUTERS

People pose in front of a floral installation with the theme of space exploration, ahead of the China's National Day, which marks the 72nd anniversary of the founding of People's Republic of China, in Beijing, China September 28, 2021. REUTERS/Tingshu Wang

Visitors stand near a JH-7AII fighter-bomber displayed at the China International Aviation and Aerospace Exhibition, or Airshow China, in Zhuhai, Guangdong province, China September 28, 2021. REUTERS/Aly Song

French President Emmanuel Macron speaks during a press conference with Greek Prime Minister during a signing ceremony of a new defence deal at The Elysee Palace in Paris, France September 28, 2021. Ludovic Marin/Pool via REUTERS

People pose in front of a floral installation with the theme of space exploration, ahead of the China's National Day, which marks the 72nd anniversary of the founding of People's Republic of China, in Beijing, China September 28, 2021. REUTERS/Tingshu Wang

Greek Prime Minister Kyriakos Mitsotakis speaks as the French President listens on, during a signing ceremony of a new defence deal at The Elysee Palace in Paris, France September 28, 2021. Ludovic Marin/Pool via REUTERS

Greek Prime Minister Kyriakos Mitsotakis speaks as the French President listens on, during a signing ceremony of a new defence deal at The Elysee Palace in Paris, France September 28, 2021. Ludovic Marin/Pool via REUTERS

People keep their social distance, as they queue up outside a cafe in a mall during the coronavirus disease (COVID-19) outbreak, in Singapore September 28, 2021. REUTERS/Edgar Su

A woman walks across a tape demarcating social distancing in a mall during the coronavirus disease (COVID-19) outbreak, in Singapore September 28, 2021. REUTERS/Edgar Su

A woman pushes her grocery cart, as she leaves a supermarket during the coronavirus disease (COVID-19) outbreak, in Singapore September 28, 2021. REUTERS/Edgar Su

People sit at a mall during the coronavirus disease (COVID-19) outbreak, in Singapore September 28, 2021. REUTERS/Edgar Su

A food delivery man leaves a mall during the coronavirus disease (COVID-19) outbreak, in Singapore September 28, 2021. REUTERS/Edgar Su

A health worker looks at a test kit at a Quick Test Centre, during the coronavirus disease (COVID-19) outbreak, in Singapore September 28, 2021. REUTERS/Edgar Su

People take their antigen rapid test under supervision, at a Quick Test Centre during the coronavirus disease (COVID-19) outbreak, in Singapore September 28, 2021. REUTERS/Edgar Su

A woman takes her antigen rapid test under supervision at a Quick Test Centre during the coronavirus disease (COVID-19) outbreak, in Singapore September 28, 2021. REUTERS/Edgar Su

German Finance Minister, Vice-Chancellor and SPD party's candidate for chancellor Olaf Scholz arrives for a meeting with his party's parliamentary group in Berlin, Germany, September 28, 2021. Tobias Schwarz/Pool via REUTERS

Germany's SPD party parliamentary group leader Rolf Muetzenich addresses the media before a meeting of the group in Berlin, Germany, September 28, 2021. Tobias Schwarz/Pool via REUTERS

A man walks next to a sign of the Youth4Climate conference in Milan, Italy, September 28, 2021. REUTERS/Flavio Lo Scalzo

Pigeons fly at dawn in front of the lava and smoke, following the eruption of a volcano on the Canary Island of La Palma, in El Paso, Spain, September 28, 2021. REUTERS/Jon Nazca

Pigeons fly at dawn in front of the lava and smoke, following the eruption of a volcano on the Canary Island of La Palma, in El Paso, Spain, September 28, 2021. REUTERS/Jon Nazca

Greek Prime Minister Kyriakos Mitsotakis speaks as the French President listens on, during a signing ceremony of a new defence deal at The Elysee Palace in Paris, France September 28, 2021. Ludovic Marin/Pool via REUTERS

Greek Prime Minister Kyriakos Mitsotakis speaks as the French President listens on, during a signing ceremony of a new defence deal at The Elysee Palace in Paris, France September 28, 2021. Ludovic Marin/Pool via REUTERS

Pigeons fly at dawn in front of the lava and smoke, following the eruption of a volcano on the Canary Island of La Palma, in El Paso, Spain, September 28, 2021. REUTERS/Jon Nazca

Greek Prime Minister Kyriakos Mitsotakis speaks as the French President listens on, during a signing ceremony of a new defence deal at The Elysee Palace in Paris, France September 28, 2021. Ludovic Marin/Pool via REUTERS

Greek Prime Minister Kyriakos Mitsotakis shakes hands with French President Emmanuel Macron following a signing ceremony of a new defence deal at The Elysee Palace in Paris, France September 28, 2021. Ludovic Marin/Pool via REUTERS

Greek Prime Minister Kyriakos Mitsotakis and French President Emmanuel Macron stand at their lecturn during a signing ceremony of a new defence deal at The Elysee Palace in Paris, France September 28, 2021. Ludovic Marin/Pool via REUTERS

Greek Prime Minister Kyriakos Mitsotakis and French President Emmanuel Macron stand at their lecturn during a signing ceremony of a new defence deal at The Elysee Palace in Paris, France September 28, 2021. Ludovic Marin/Pool via REUTERS

Greek Prime Minister Kyriakos Mitsotakis speaks as French President Emmanuel Macron listens on during a signing ceremony of a new defence deal at The Elysee Palace in Paris, France September 28, 2021. Ludovic Marin/Pool via REUTERS

Lava and smoke are seen at dawn from El Paso following the eruption of a volcano on the Canary Island of La Palma, Spain, September 28, 2021. REUTERS/Jon Nazca

Greek Prime Minister Kyriakos Mitsotakis shakes hands with French President Emmanuel Macron following a signing ceremony of a new defence deal at The Elysee Palace in Paris, France September 28, 2021. Ludovic Marin/Pool via REUTERS

Greek Prime Minister Kyriakos Mitsotakis shakes hands with French President Emmanuel Macron following a signing ceremony of a new defence deal at The Elysee Palace in Paris, France September 28, 2021. Ludovic Marin/Pool via REUTERS