Speaking at an event in Rawalpindi on Sunday, General Sharif said: "Let me reiterate that our armed forces stand fully capable to defeat all sorts of external aggression."
The comments were seen as a direct response to Indian Army Chief Dalbir Singh Suhaag saying last week that India has to be prepared for "swift, short nature of future wars" because of frequent ceasefire violations by Pakistan and its "new methods" used to keep Jammu and Kashmir on the boil.
The Pakistan Army Chief said: "If the enemy ever resorts to any misadventure, regardless of its size and scale - short or long - it will have to pay an unbearable cost."
Saying that innocent people were "subjected to injustice, atrocities in Kashmir", General Sharif said: "Enduring peace is not possible without a just resolution of Kashmir. The issue can no longer be put on the backburner."
The time had come, he said, for Kashmir to be resolved "in line with UN resolutions."
The Pakistan army chief was speaking at an event to mark the 1965 war with India.
At an event in Delhi to commemorate the same war, the Indian Army chief had said that the borders were live and active because of frequent ceasefire violations and infiltration bids by Pakistan.
"We are acutely aware that the swift, short nature of future wars are likely to offer limited warning time - this calls for maintaining very high levels of operational preparedness at all times," said General Singh.
The remarks come amid heightened tensions over cross-border firing between Indian and Pakistani troops.
National Security Level talks between India and Pakistan last month were cancelled at the eleventh hour amid major disagreements over the agenda for talks. India said the ceasefire violations and attacks by Pakistan-based terrorists must be discussed but Pakistan insisted that it would raise Kashmir.
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