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Russian forces could face a sustained and bloody insurgency lasting years if it topples the Ukraine government and appoints a puppet administration, a leading think tank has said.
It also predicted the situation could echo Syria or Iraq, with many local militias fighting it out as more and more weapons are pumped into the country.
These are some of the key findings of a briefing on the Russian attack on Ukraine by the Institute for Economics and Peace (IEP), which produces the annual Global Terrorism Index.
Ukraine remains in control of most major cities but the briefing from the Sydney-based think tank suggested deaths from terror attacks in Ukraine are likely to increase in the coming months and that this would rise proportionally with the intensity of the conflict.
“If Russia does capture Kiev and gets the government to fall, they will try to install a puppet government,” said Steve Killelea, founder and executive chairman of the IEP.
“The obvious question is would that government be able to stand without strong support from the Russian military?”
The most likely outcome would be a prolonged insurgency lasting for several years, said Mr Killelea.
The briefing on the crisis in Ukraine was released along with the IEP’s annual Global Terrorism Index, which looked at the impact of terrorist incidents around the world over the past 12 months.
The invasion, which began last month, came after a decade of deteriorating relations between Russia, Ukraine and the West, the IEP briefing said.
“Just like what happened with Iraq, the likelihood is there will be more weapons pumped into Ukraine,” said Mr Killelea.
“This will give Ukrainian insurgents the ability to mount a sustained campaign against whatever government would be in place.”
He also warned of the potential of civil militia groups to rise up and attack each other, a situation that was prevalent in Syria and Iraq where conflict was sustained over long periods.
The most likely region of Ukraine to be affected by insurgencies is Donbas, Mr Killelea said.
The UN has estimated that armed conflict in the south-eastern part of Ukraine between government forces and Russian-backed separatists has killed more than 14,000 people since 2014.
“You could see different militias arise and start to attack each other,” said Mr Killelea.
“One of the ways this things go is the Russians can try to enlist or create local militias and then you have those who want to free Ukraine who will be fighting back.
“Obviously we are not at that stage yet but it is a possibility.”
The briefing also warned of the threat posed to the wider world by the rise of cyber attacks on Ukraine by Russia.
“If the conflict is not unfolding as Russia had hoped and it perceives the flow of weapons from European countries to Ukraine as hostile, it may order hackers to extend their reach to paralyse those opposing Russian efforts,” the briefing said.
Another expert unrelated to the think tank's briefing said an insurgency is likely if Mr Putin is able to topple the current regime in Ukraine.
“What he will leave behind is a country that doesn’t want him there,” said Sean Bell, a former air vice marshal who served with the UK military and is now an adviser with global defence consultants UDSS.
“He will be seen as an alien, like a virus and the nationals will certainly want to find ways to get rid of him.
“He will find it very difficult to run the country and there will probably be a lengthy insurgency against him.”
He said the insurgency could mean Ukraine becomes like Nazi-occupied France.
“It will be a bit like France during that period, with a resistance against an occupying power to make as difficult as possible for them,” added Mr Bell.