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4 year old"It is about forest management. Please remember the words, very simple, forest management," he told a campaign rally in Nevada.
So is poor forest management responsible for these worsening fires?
Firstly, most forest in California, Oregon and Washington isn't the responsibility of the state authorities - in fact, their share of forest land is small.
In California state, the federal government owns nearly 58% of the 33 million acres of forest, according to the state governor's office. The state itself owns just three per cent, with the rest owned by private individuals or companies or Native American groups.
There's a similar picture in Oregon, with significant proportions of forest land in federal rather than state hands, as well as under private ownership.
And in Washington state, only 12% of forest land is in the hands of the state authorities, with 43% federally-owned and 36% in private hands.
Federal agencies like the US Forest Service, the Bureau of Land Management and the National Parks Service are responsible for the upkeep of federally-owned land, and as far as private forest land is concerned, it's up to the owners to manage these areas.
Two years ago, President Trump also criticised California's forest management. He pointed to Finland, where he said they raked and cleared the forests to prevent fires.
Finland is not directly comparable to California due to differences in climate, types of vegetation and land use.
But experts believe there are issues with forest management practice and land use across California and elsewhere.
Scott Stephens, a leading authority on wildfires, at the University of California, has for some years questioned forest management priorities.
He's pointed to the large number of dead trees left standing in parts of the state, due to drought and disease, as a serious fire risk that needs to be addressed.
Prof Stefan Doerr, a wildfires expert at Swansea University, points to the modern practice of total fire suppression, at the expense of allowing some limited fires to burn and create firebreaks.
"For centuries, Native American peoples would burn parts of the forest... and that would thin out more flammable vegetation and make forests less dense.
"But the emphasis has been on putting out any fires - and with climate change this has now created a tinderbox of vegetation," says Prof Doerr.
The US Forest Service has been trying to rectify this in recent years through setting fires in what's called "controlled burning."
However, there are questions about whether enough resources are being devoted to this, and if it's really come too late in the day to prevent major fires.
The Governor of Washington State, Jay Inslee, has acknowledged that "there are places where it makes sense that we thin our timber. And we are doing that."
But he also criticised President Trump for highlighting this factor, rather than climate change: "These are climate [change] fires."
Drier, warmer conditions lead to vegetation drying out and becoming more flammable. Add to that the fact that winter seasons when it rains or snows are getting shorter by the year.
In terms of loss of life and damage to property, the data shows the worst fires have all been in the past 10 years or so - except for one fire in 1991 in Alameda County.
And this year, there have also been unusually strong winds combined with periods of drought across parts of the western US. Six of the largest fires recorded in California have all happened this year.
Prof Doerr says a combination of drier, hotter and windy conditions is the key factor in these recent fires: "The bottom line remains that the extreme meteorological conditions are the main drivers for these extreme fires."
A key issue is the increasing number of people moving out of urban areas to live near forests, known as the wildland-urban interface.
One 2018 study for the Proceedings of the National Academy of Sciences in the US, estimated about one in three homes were now in such areas.
This growth poses several problems:
A report in 2015 for the US Department of Agriculture warned that the expansion of the wildland-urban interface "has increased the likelihood that wildfires will threaten structures and people."
This article was originally published in November 2018. It has been extensively revised.
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