On the night between December 20-21, a group of terrorists attempted to attack security forces check post in general area Makeen in the tribal district, the Inter-Services Public Relations (ISPR) said in a statement.It said the attempt was effectively thwarted by troops and in ensuing fire exchange, "eight khwarij [terrorists] were sent to hell". "However, during intense fire exchange, sixteen brave sons of soil, having fought gallantly embraced shahadat."The ISPR said sanitisation operation was launched in the area and the perpetrators of the heinous act will be brought to justice."Security forces of Pakistan are determined to eliminate the menace of terrorism and such sacrifices of our brave men further strengthen our resolve."Earlier today, a Pakistan Army soldier embraced martyrdom and four terrorists were neutralised after security forces successfully thwarted a bid to infiltrate the Pakistan-Afghanistan border in Khyber district, Khyber Pakhtunkhwa, the military's media wing said.The ISPR had said that the troops engaged the terrorists after their movement was picked in Rajgal area in the night between December 19 and 20.The statement also underscored Islamabad's persistent calls urging Kabul's interim government to "fulfil its obligations and deny the use of Afghan soil by [terrorists or khwarij] for perpetrating acts of terrorism against Pakistan".