A helicopter drops fire retardent to protect a property in Balmoral, 150 kilometres southwest of Sydney on December 19, 2019. A state of emergency was declared in Australia's most populated region on December 19, as a record heat wave fanned unprecedented bushfires. (Photo by Peter Parks/AFP Photo)

Russian President Vladimir Putin, right, and North Korea's leader Kim Jong Un pose for photographers during their meeting in Vladivostok, Russia, Thursday, April 25, 2019. Putin and Kim are set to have one-on-one meeting at the Far Eastern State University on the Russky Island across a bridge from Vladivostok. The meeting will be followed by broader talks involving officials from both sides. (Photo by Alexander Zemlianichenko/AP Photo/Pool)

A house along Hoover Beach is covered by ice from high winds and from the waves from Lake Erie, Saturday, February 29, 2020, in Hamburg N.Y. Blowing snow has fallen around the state since Thursday, though the heaviest snowfall was concentrated in largely rural areas east of Lake Erie and Lake Ontario. (Photo by Jeffrey T. Barnes/AP Photo)

South Korean environmental activists wearing masks symbolizing the coronavirus attend a prevention campaign as South Koreans take measures to protect themselves against the spread of coronavirus (COVID-19) on March 30, 2020 in Seoul, South Korea. South Korea has called for expanded public participation in social distancing, as the country witnesses a wave of community spread and imported infections leading to a resurgence in new cases of COVID-19. According to the Korea Center for Disease Control and Prevention on Monday, 78 new cases were reported. The total number of infections in the nation tallies at 9,661. (Photo by Chung Sung-Jun/Getty Images)

A policeman wearing a coronavirus-themed outfit composed of helmet, mace and shield, gestures towards a vendor (L) at a market to raise awareness about social distancing, during a government-imposed nationwide lockdown as a preventive measure against the COVID-19 coronavirus in Chennai, on April 2, 2020. (Photo by Arun Sankar/AFP Photo)

A lady wearing a mask feeds pigeons in St James' Park, as the spread of the coronavirus disease (COVID-19) continues, London, Britain, April 5, 2020. (Photo by Henry Nicholls/Reuters)

A specialist from a local veterinary service wears a protective suit as sprays disinfectant near Russian tanks displayed at area near Proryv (The Breakthrough) museum dedicated to the breakthrough of the Siege of Leningrad during World WarII near Kirovsk, about 30 kilometres (19 miles) east of St.Petersburg, Russia, Thursday, April 2, 2020. (Photo by Dmitri Lovetsky/AP Photo)