"... the regime have used to strike ..."

[Odessa Dawn]

"Rebels also claimed to have seized an oilfield near Deir Al-Zour, while fighting continued around army and airbases west of Aleppo, which the regime have used to strike rebel-held areas in recent weeks."

"I am shocked to see Bashar do what he has doing," he said. "He used to seem like a good human being, but he is worse than his father."

More: Bashar al-Assad wants war not peace reveals Syria's former prime minister Riyad Hijab - Telegraph

I am somewhat familiar with used to / be used to usage, but I am stuck with "have used to."

[5jj]

There is no 'have used to'. It is 'have used' followed by '(from which) to strike ...'.

[Odessa Dawn]

There is no 'have used to'. It is 'have used' followed by '(from which) to strike ...'.

Thank you 5jj. So, the aforementioned sentence has been constructed in present perfect simple tense, hasn't it?

[5jj]

Thank you 5jj. So, the aforementioned sentence has been constructed in present perfect simple tense, hasn't it?

There are different tenses in that sentence. 'Have used' is present perfect.