Siberia is burning.

Almost three million hectares of land in the centre and east of the nation were on fire, officials said, roughly about the size of Belgium.

The situation has reached such proportions, that Russian president, Vladimir Putin, has called in the army to fight the forest fires that are now enveloping entire cities in black smoke, The Guardian reported.

Environmentalists have even warned that the scale of the blazes could accelerate global warming, aside from any immediate effects on the health of inhabitants. A state of emergency has been declared in five regions.

“The forest fires in the eastern part of the country have long stopped being a local problem,” the Russian branch of Greenpeace said in a statement. “It has transformed into an ecological disaster with consequences for the entire country.”

The acrid smoke has affected small settlements as well as cities in Western Siberia and the Altai region, and also the Urals such as Chelyabinsk and Yekaterinburg, the report said.

Commercial air travel over these areas have also been disrupted.

“After reviewing a report from the emergency situations minister, Putin instructed the ministry of defence to join the effort to extinguish the fires,” the Kremlin’s press service told Russian media.

Approximately 2,700 firefighters were tackling the fires, Interfax news agency reported. The defence ministry told news organizations that 10 planes and 10 helicopters had been dispatched to the Krasnoyarsk region, one of the worst affected.

The fires, triggered by dry thunderstorms in temperatures exceeding 30C (86F), were spread by strong winds, Russia’s federal forestry agency said.

Meanwhile, Prime Minister Dmitry Medvedev ordered Russian police to investigate if  the wildfires in Siberia could have been started deliberately to conceal illegal logging activity, TASS reported.

Russia‘s Investigative Committee also said it had opened a criminal case over the fires and was investigating officials in the Siberian city of Krasnoyarsk for possible negligence at having not taken action to stop them.

Anton Beneslavsky, a Greenpeace activist, however, said the fires were caused by a combination of climate change and what he said were ineffective measures in place to bring forest fires under control, Global News reported.

The Kremlin has also confirmed that US President Trump phoned President Putin this week, declaring that the United States was ready to assist Russia in fighting wildfires, The Telegraph reported.

Putin said he would keep it in mind, and took the offer as a sign bilateral relations could be improved, the report said.

Italian Prime Minister Giuseppe Conte also wrote in his Twitter account: “In connection with the emergency situation with fires in Siberia, I suggested that the Russian Federation cooperate with our civil protection department by providing two Canadair aircraft in the hope that the situation will normalize soon.”