JERUSALEM (AP) -- Israel's air force chief warned Wednesday that tensions with Syria could escalate into a "surprise war" and that Israel needs to be ready.

The remarks by Maj. Gen. Amir Eshel echoed statements by Israel's military chief of staff a day earlier.

"A surprise war could take shape today in many configurations," Eshel said at a strategy conference in Herzliya, near Tel Aviv. "Isolated incidents can escalate very quickly and require us to be prepared in a matter of hours to operate throughout the entire spectrum ... to utilize all the capabilities of the air force," he said.

He said Russian S-300 air defense systems are "on their way" to Syria, though Israel asked Russia not to supply the advanced air defense system to Syria.

Israel has been warily watching the Syrian civil war since it broke out in March 2011, concerned that the conflict could spill across its borders at any time.

Syrian and Israeli forces briefly exchanged fire on the Golan Heights border Tuesday, prompting Israel's military chief, Lt. Gen. Benny Gantz, to accuse Syrian President Bashar Assad of encouraging and directing operations against Israel and warning he would "bear the consequences" of escalation.

Tensions have been rising between Israel and Syria in recent weeks. Israel is believed to have carried out airstrikes said to be aimed at weapons meant for the Lebanese Hezbollah. Israel has not confirmed carrying out the attacks.

Israel has warned it will not tolerate fire from Syria or transfer of advanced weapons to militants. Israel is concerned that Syria's arsenal, including chemical weapons, anti-aircraft systems and sophisticated missiles, could be transferred to Hezbollah or fall into the hands of rebel groups linked to al-Qaida.

"Syria is changing before our eyes. If tomorrow it collapses, we could very quickly find that great arsenal dispersed and directed at us," Eshel said.