Are Afghan refugees in Pakistan a security threat?

Two and a half million Afghan refugees living in Pakistan could be sent back, despite not being born in Afghanistan and never having lived there.

Citing security concerns, Pakistan says the refugees must leave the country by the end of the year.

It is a decision described by rights groups as "one of the largest forcible returns of refugees in modern history".

Afghan refugees have been living in Pakistan since the early 1980s, when they fled from Soviet invasion.

Pakistan has hosted more than three million Afghan refugees over the past several decades.

The government has repeatedly set and extended deadlines for the refugees to leave.

But it says this year is final, calling it a matter of national security.