Gulbuddin Hekmatyar was due to meet Afghan President Ashraf Ghani after arriving in the capital Kabul on Thursday.

A heavily armed convoy escorted the notorious warlord - infamous for shelling Kabul in the early 1990s during the Afghan civil war - from eastern Nangarhar province to Kabul, the interior ministry and Hekmatyar's spokesman confirmed.

The former Afghan premier is set to play an active role in politics following a deal in September last year between the Afghan government and his militant group, Hezb-i-Islami.

In February, the UN Security Council lifted sanctions against Hekmatyar, which included a freeze that had been put on his assets, a comprehensive travel ban and an arms embargo.

Hekmatyar, the leader of the Islamist organization Hezb-i-Islami, had occasionally collaborated with al-Qaeda and the Taliban after the 2001 US-led invasion of Afghanistan. He was Afghanistan's prime minister from 1993 to 1994, and again briefly in 1996, before the Taliban took over Kabul.

The powerful warlord's return comes at a time when US President Donald Trump is reviewing his country's Afghan policy and is likely to announce a new strategy in the coming weeks.

Hekmatyar is set to play an active role in Afghan politics

The involvement of Russia in Afghan politics has also increased substantially in the past few months, with many analysts suggesting that Moscow aims to minimize Washington's role in Afghanistan with the help of Islamabad and Beijing. US officials hinted last month that Russia is arming Taliban insurgents.

Peace process

Members of Afghanistan's High Peace Council, the body tasked with forging reconciliation with the Taliban and other armed groups, believe Hekmatyar could pave the way for other militant groups like the Taliban to join the government.

President Ghani's National Unity Government is under pressure for failing to reach a peace agreement with the Taliban or with other armed groups. Efforts by Afghanistan to reconcile with the Taliban using Pakistan's support seem to have hit a dead end, with Kabul blaming Islamabad of not fulfilling its promises.

Amid worsening ties with Afghanistan and the US, Pakistan has drifted closer to China and Russia and has sought their help to end the Afghan conflict.

Hekmatyar is believed to have good relations with Pakistan's military establishment, but unexpectedly the former premier warned Afghanistan's neighbors against meddling in his country's internal matters.

"I hope that our neighbors do not make Afghanistan into a battlefield for their political and military rivalry," Hekmatyar said on April 29 in his first public appearance in nearly two decades.

He also urged Taliban insurgents to join a "caravan of peace."

"Stop the pointless, meaningless and unholy war," Hekmatyar told a gathering of his followers and Afghan politicians in Laghman province, east of the capital, Kabul.

Are the Afghan Taliban willing to sign a similar peace deal with Kabul?

A divisive figure

Some experts are of the view that the Afghan government's engagement with Hekmatyar could be risky.

"There are still uncertainties as to what he is going to do," one senior official in the Afghan government told Reuters news agency on condition of anonymity. "Is he going to be a partner in the government or a rival?"

Hekmatyar's return is also likely to intensify the schisms between various factions in the unity government. Chief Executive Abdullah Abdullah and his Tajik supporters would be perturbed by the influential Hezb-i-Islami leader's return, with many believing it will further entrench Pashtun dominance in the government.

"Hekmatyar's rhetoric about being dominant and controlling has never changed and he is after power and authority," said Abdul Hodod Paiman, a Tajik member of parliament from Hekmatyar's home city of Kunduz.

Is the Afghan unity government falling apart?

But others hope he could bring much-needed peace to the war-torn country.

"He is an influential figure and has a lot of support across the country and he can be a key in bringing peace to the country," said Safiullah Muslim, a member of parliament from the northern province of Badakhshan.

Some observers believe the Afghan government's main concern right now is the expansion of the so-called "Islamic State" (IS) group in the country. Kabul, with the help of Hekmatyar and the Taliban, can stop the IS advance, and Washington and Moscow appear to be on the same page on this issue.

Negotiating from a weak position

On the other hand, President Ghani is facing major internal challenges. The government's approval rating has been decreasing, and the Islamist insurgency seems bloodier than ever.

A major anti-government protest in Kabul in May last year highlighted the fragile political situation in the country and the decline in support for Ghani's administration among Afghans.

This is why experts believe Ghani wants to strengthen his support among Pashtuns who supported Hekmatyar during Afghanistan's civil war in the 1990's.

"Hekmatyar still has a lot of support among people all over Afghanistan, and his union with the government can bring a lot of new people to their side," Faiz Mohammad Zaland, a lecturer at Kabul University, told DW.

Also, Hekmatyar's close ties with Pakistan could help improve Kabul's tense relations with Islamabad. At the same time, some experts warn that the Afghan government should be cautious about Pakistan's increased role in Afghan politics.

Additional reporting by Masood Saifullah and Waslat Hasrat-Nazimi.