Kosovo broke from Serbia in 1999 and declared independence in 2008. But Serbia has not recognised the move and sees its former province as part of its territory.
Serbian President Aleksandar Vucic has ordered combat readiness for the armed forces and security services at the highest level, said Defense Minister Milos Vucevic.
The aim is to protect the territorial integrity of Serbia, he said on Monday.
“It raises us to the highest level of action carried out by the Serbian Army, protecting the territorial integrity and sovereignty of Serbia and protecting all citizens of Serbia and preventing terrorism and terror against Serbs wherever they live,” said Vucevic.
Interior Minister Bratislav Gasic said Vucic also ordered security forces within the ministry to be at full combat readiness.
"I have ordered the full combat readiness of all units of the ministry… as soon as they are placed under the command of the Chief of General Staff and occupy the designated positions operational plan," said Gasic.
READ MORE: NATO general says able to secure Kosovo as Serbia tries to deploy troops
Kosovo, predominantly inhabited by Albanians, broke from Serbia in 1999 and declared independence in 2008. But Serbia has not recognised the move and sees its former province as part of its territory.
Tensions between Kosovo and Serbia have escalated since the detention of former Serbian police officer Dejan Pantic.
Reacting to Pantic's detention, Kosovo Serbs have been standing guard at barricades they set up at the Jarinje and Bernjak border crossings since December 10.
The European Union, NATO and the US have called for de-escalation and the removal of barricades in northern Kosovo, while Serbia has requested to deploy its army and police based on a UN resolution.
READ MORE: Why tensions have flared up between Kosovo and Serbia