Pakistan is sending troops to ally Saudi Arabia on a "training and advise mission", the military said, three years after it decided against sending soldiers to join the Saudi-led military intervention in Yemen.
The exact role the troops will play was unclear, but a statement from the army's press wing on Thursday stressed they "will not be employed outside" the kingdom.
Pakistan's retired army chief, General Raheel Sharif, commands the new Saudi-led Islamic military alliance to fight terrorism, though it was not immediately clear whether the new troops would participate in that coalition.
Saudi Arabia had asked fellow Sunni-majority Pakistan to provide ships, aircraft and troops for the Yemen campaign to stem the influence of Shia Iran in what appears to be proxy war between the Gulf's two dominant powers.
Pakistan's parliament voted to remain neutral to avoid being pulled into a sectarian regional power struggle, in part because the country shares a border with Iran and has a sizeable Shia minority.
Pakistani military analyst retired Brigadier Shaukat Qadir said talks involving sending troops to Saudi Arabia had been ongoing for some time.
"Now, apparently, for whatever reason, the decision has been taken," he said.
There are already about 750-800 Pakistani servicemen in Saudi Arabia, in part to guard Islamic holy sites, but they are not combat troops.