Turkey will treat any Syrian military units which approach its border as a threat and a military target, Prime Minister Tayyip Erdogan said on Tuesday.
Erdogan also said Turkey was totally in the right over Syria's shooting down of a Turkish plane and that Ankara's rational response to the incident should not be mistaken for weakness.
"Everybody should know that Turkey's wrath is just as strong and devastating," Erdogan said in a speech to his ruling AK Party deputies in parliament.
The army's rules of engagement along the two countries' border had now changed, he said.
"Every military element approaching Turkey from the Syrian border and representing a security risk and danger will be assessed as a military threat and will be treated as a military target," he said.
Turkey has rejected assertions from Damascus that its forces had no option but to fire on the F-4 jet as it flew over Syrian waters close to the coast on Friday and has branded the shooting an "act of aggression". It says the aircraft was an unarmed reconnaissance plane flying over international waters.
The incident has heightened tensions between Turkey and Syria already strained over the 16-month uprising against Syrian President Bashar Assad's rule.
Turkey has demanded backing from its NATO allies over the shoot down and called a meeting in Brussels under Article 4 of the alliance's charter, which provides for consultations when a member state feels its territorial integrity or security is under threat.
NATO member states condemned Syria on Tuesday for shooting down the Turkish jet, calling it "unacceptable" and demanding that Damascus take steps to prevent further incidents.
"NATO allies have expressed strong condemnation of this completely unacceptable act," NATO Secretary-General Anders Fogh Rasmussen said after the gathering.
Rasmussen said NATO security was "indivisible", but he said NATO's Article 5, which calls for member states to see an attack on one country as an attack on all the alliance's members, had not been discussed.
"We stand together with Turkey in spirit of solidarity," he said.