An attempted ISIS attack in the US is now an “inevitability” as the terror group has a “strong desire” to strike the country, the former head of US Central Command has warned.

Retired Gen. Frank McKenzie told ABC News that officials should “believe them when they say that.”

He warned: “I think the threat is growing. It began to grow as soon as we left Afghanistan, it took pressure off ISIS-K.

“So I think we should expect further attempts of this nature against the United States, as well as our partners and other nations abroad. I think this is inevitable.”

His comments come after ISIS-K, a faction of the group based in Afghanistan, killed over 130 people in a terror attack in Moscow last month.

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The former US Central Command chief is not alone in his warnings. An expert recently told Daily Express US that capitals across Europe and North America are vulnerable to ISIS attacks.

Lucas Webber even warned that the US election could be targeted.

He said: “There are major sporting events in Germany and France this summer, there is the election in the US, and there is concern in Canada, the US, and across Europe.

“This is a well-founded concern. The US was among the first to warn of the threat prior to the Moscow attack.

“History shows us that in the future we are going to see more and more threats from ISIS-K.”