Alexander Bortnikov said the terrorist group's newest tactic is setting fires that "allow them to inflict significant damage on the economy and morale" of countries, the Russian news agency RIA Novosti reported.
He told a security and law enforcement meeting of Russian and partner states extremist websites have been talking about "forest jihad," and providing suggestions on the most effective ways of starting a forest fire.
Bortnikov said setting fires doesn't require serious preparation, technical equipment or financial outlay.
Security services have only minimal chances of catching arsonists, he said.
Forest fires have become an annual occurrence in Europe in recent years.
Southern European countries like Spain, Italy, Portugal, Montenegro, Greece and Serbia have been particularly hard-hit by forest and wildfires.
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