Image copyright EPA Image caption A military campaign against militant groups has growing popular support in Pakistan

The militant group Islamic State has its heartland in Iraq and Syria, but recent reports suggest it is now intent on building a presence in Afghanistan and Pakistan.

IS has even named a regional leader for South Asia - a former Pakistani Taliban commander, Saeed Khan.

Afghanistan and Pakistan are already beset with militancy, and there are fears that IS involvement could escalate an already volatile situation.

Should we be worried?

Militants in southern Afghanistan continue to be mostly loyal to Taliban leader Mullah Omar. There is little evidence of any prominent Afghan groups joining IS, except a disaffected commander in the Helmand region.

Image copyright AFP Image caption Graffiti in support of Islamic State has been seen in parts of Pakistan

In Pakistan, the army exercises almost total control. At times, it has seemed like the state was experiencing trouble from the Taliban. But that has been mainly because, as most analysts believe, the army has been using militants to achieve its own strategic aims in Afghanistan and India.

There is evidence that groups marginalised by the military offensive in North Waziristan have been toying with the idea of joining IS to re-energise their local presence.

As a result, pro-IS slogans have been chalked on walls, black IS flags have appeared, and some pamphlets have been distributed in various parts of Pakistan.

At least one official note by the provincial government of Balochistan in the south-west said some local sectarian groups were recruiting fighters on behalf of IS.

But so far only Saeed Khan and his group have announced allegiance to IS.

Who is Saeed Khan?

Between 2009 and 2014, he served as Pakistani Taliban commander for his native Orakzai tribal district in the north-west, before he pledged allegiance to IS in a video released last October.

His clout has been limited to Orakzai, and his elevation to regional IS leader comes while he is on the run, looking for reported hideouts in north-eastern Afghanistan.

Said to be in mid-40s, Saeed Khan studied religion at seminaries in the Mamozai area of Orakzai and in the neighbouring province of Khyber Pakhtunkhwa (then North West Frontier Province).

After 9/11, he fought the coalition forces in Afghanistan and came under the influence of then Pakistani Taliban leader Baitullah Mehsud.

Image copyright AP Image caption Saeed Khan was a protege of Baitullah Mehsud (left)

Saeed Khan took charge of Orakzai in August 2009 when Baitullah Mehsud was killed in a drone strike and Orakzai chief Hakimullah Mehsud replaced him as overall leader.

Saeed Khan is said to have had differences with Hakimullah Mehsud, who was killed in another drone strike in 2013. He also opposed the elevation of Mullah Fazlullah, Hakimullah Mehsud's successor.

This was probably the reason he quit the Taliban and joined IS.

Have other militants reacted?

Ayman al-Zawahiri announced the formation of al-Qaeda in the Indian Sub-Continent just two months after IS chief Abu Bakr al-Baghdadi declared himself Caliph in June 2014.

Weeks later it launched a major attack on the Pakistani naval installations in Karachi. Many believe al-Qaeda did it to prevent IS from eroding its influence with potential recruiting channels and rich Middle Eastern donors.

Image copyright AFP Image caption A school massacre in Peshawar might have been indirectly caused by Islamic State

There is also speculation that Mullah Fazlullah's group carried out the massacre of school children in Peshawar last month to match the brutality of IS before the IS regional chief Saeed Khan could launch his own maiden attack in the region.

Does IS have any links with South Asia?

Since the late 1990s, all leaders of militant groups in the region have remained loyal to the head of the Afghan Taliban, Mullah Mohammad Omar.

This includes IS founder Abu Musab al-Zarqawi, who spent several years in Afghanistan before he began fighting in Iraq.

Image copyright Getty Images Image caption IS founder Abu Musab al-Zarqawi had Afghan links

The IS leaders who have followed him have had little or no experience of Afghanistan and Pakistan, and no personal links.

Their only link to the region is the local and foreign fighters who have been flocking to Syria and Iraq from Afghanistan during the last few of years.

Can they really make an impression?

A crucial factor remains the Pakistani army - it is believed to be the main force that sustains Islamist militant networks in the region, a suggestion that is officially denied.

Image copyright AFP Image caption Pakistan's army remains the real power in the region

Afghan militant groups also continue to depend on Pakistani support and supplies, according to analysts.

But Pakistan's army has also demonstrated its ability to eliminate militant sanctuaries at will, like it did in Swat in 2009, or in North Waziristan last year.

Most analysts believe IS cannot make inroads into the region unless the Pakistani military allows it.