Five soldiers of the Pakistan Army lost their lives in a cross-border "terrorist attack" on three Pakistani border posts along the Pak-Afghan border area on Sunday night.

Pakistan Army reportedly killed over 15 suspected terrorists in their retaliatory action and injured 20 others, according to a press release issued by Inter-Services Public Relations (ISPR).

It further said that there are "credible reports" that six of the 15 militants who were killed Sunday night were "operational level terrorists", namely Kuchay Bajuari, Zar Mohammad alias Madni, Huzaifa, Sangary, Lakhkari and Sangeen

ISPR said "terrorists" from across the border had targeted the posts late on Sunday night in Mohmand Agency.

"Effective presence, vigilance and response repulsed terrorists attempt," read the statement.

The slain soldiers were identified as Naik Sanaullah, Naik Safdar, Sepoy Altaf, Sepoy Nek Mohammad and Sepoy Anwar.

Chief of Army Staff (COAS) Qamar Javed Bajwa appreciated the response by Pakistani troops to the militant attack in Mohmand Agency. He said: "Terrorists are [a] common threat and must be denied freedom of movement/action along the border."

The army chief emphasised the need for physical presence of troops on Afghan side of the border for "matching [the Pakistani side] and effective border security".

The COAS expressed grief on loss of precious lives and hailed the slain soldiers' sacrifice.

The foreign office summoned the Afghan Deputy Head of Mission and conveyed Pakistan's grave concern over the incidents, Radio Pakistan reported.

According to Radio Pakistan, the Afghan government was urged to investigate the incident and take action against terrorists from their side of the border.

The message that effective border management is important to prevent cross-border terrorist movement has also been sent across, said Radio Pakistan.

PM Nawaz condemns attack

Prime Minister Nawaz Sharif said the sacrifices rendered by the country's soldiers while defending the motherland were the “real lifeline of nation.”

“The soldiers who sacrificed their life are our real heroes and the nation promises to honour them by standing firm against terrorists nefarious designs to hit at our way of life,” PM Nawaz said in a statement condemning the attack.

He expressed grief over the martyrdom of army personnel who lost lives while engaging with the suspected militants.

The prime minister said that Pakistan would become stronger, “because our men in uniform are vigilant at our borders and in urban centres.”

“Terrorists are mistaken if they think they can weaken the resolve of our nation,” he said.

The premier said operation Raddul Fasaad was against every terrorist working from with in the country or operating from a foreign territory.

“The enemies of Pakistan will be eliminated along with their cancerous ideology,” he said.

Tense relations

The latest attack comes at a time when bilateral relations between Afghanistan and Pakistan are already soured.

Following a spate of terror attacks in which more than 100 people were killed last month, Pakistan had sealed its border with Afghanistan. Pakistan had held Afghanistan-based militant groups responsible for carrying out the attacks in Pakistan.

The Pakistan Army had later targeted militant hideouts close to the Pak-Afghan border. The army had reportedly targeted a training camp of Jamaat-ul-Ahrar — the banned terror outfit which claimed responsibility for the Feb 13 suicide bombing in Lahore and the Feb 15 suicide attack on the headquarters of the Mohmand Agency's political administration.

The army had asked Kabul to take action against 76 Pakistani terrorists operating from Afghan territory or hand them over to Pakistan so that they could be tried for their involvement in terror-related activities.

In response, Afghanistan delivered a list of 85 Taliban and Haqqani Network leaders and 32 terror camps on Pakistani soil, which it claimed were involved in “crimes against people of Afghanistan”.

Mohmand is one of Pakistan’s seven semi-autonomous tribal districts near the Afghan border, rife with homegrown insurgents and foreign militants.

Despite heavy military presence on both sides of the border, cross-border movements of militants (in both ways) have been a major area of concern.

Local militants have fled ongoing military offensives since 2008, taking refuge across the border and attacking Pakistani military checkpoints and civilians from there.