BEIRUT - Hezbollah leader Sayyed Hassan Nasrallah said on Friday that a future war waged by Israel against Syria or Lebanon could draw thousands of fighters from countries including Iran, Iraq and Yemen.His comments indicated that the same array of Iranian-backed Shi'ite militias - but not countries - currently fighting in Syria in support of President Bashar Assad could take part in any future conflict with Israel."The Israeli enemy must know that if an Israeli war is launched against Syria or Lebanon, it is not known that the fighting will remain Lebanese-Israeli, or Syrian-Israeli," Nasrallah said in a televised speech."This doesn't mean there are states that might intervene directly. But this could open the way for thousands, even hundreds of thousands of fighters from all over the Arab and Islamic world to participate," he said.Nasrallah has repeatedly warned Israel against attacking Lebanon, where the Iran-backed Shi'ite group is based, and from where it sends fighters to support Assad against insurgents.Experts on the group say the warnings are part of a policy of deterrence that has also included revealing some of its military capabilities.Nasrallah said in recent months Hezbollah's rocket arsenal can hit any military target in Israel, which is Lebanon's southern neighbor.He also said any Israeli war with Lebanon or the Gaza Strip, which is run by Hamas, would be "very costly" and that Israel would not be able to win.Israel has allegedly targeted senior Hezbollah commanders in air raids on Syrian soil. But there has been no major confrontation between Hezbollah and Israel in Lebanon since a month-long war between the two sides in 2006.Israel Air Force Commander Maj.-Gen. Amir Eshel said Israel would use all its strength from the start in any new war with Hezbollah.“What we could do in 34 days during the Second Lebanon War, we can now do in 48 hours. The growth of our strength has not been linear,” he told the Herzliya Conference at the Interdisciplinary Center on Wednesday. The IAF has not only improved in the speed with which it can attack, but also the volume said Eshel, noting that the IDF could hit Hezbollah “with four to five times” the bombing power it used during the 2006 war.In addition, Eshel warned civilians in southern Lebanon to leave their homes if war with Israel breaks out, saying, “one in every four or five homes has weapons hidden in it,” leaving the air force no choice but to strike.Yonah Jeremy Bob contributed to this report.