The leader of Lebanon's Hezbollah said Thursday that keeping the militant group's arsenal a "secret" is part of its battle against Israel and that his guerrillas won't be frightened by Israeli threats to attack Lebanon.

Hassan Nasrallah made a point of not disclosing whether his guerrillas now have anti-aircraft missile systems that could stand up to Israeli air raids.

"There has been an Israeli uproar about the reinforcement of Hezbollah's strength. There has been talk of sophisticated arms and an air defense system and threats if Hezbollah uses this kind of system," Nasrallah said.

"No one can expect me to stand up and say (whether) we possess new weapons or we don't," he added. "Keeping (weapons) secret is part of ... (Hezbollah's) strength. This is part of directing the battle of liberation and resistance against this (Israeli) enemy."

Nasrallah's remarks came during a televised speech to supporters Thursday night, marking the second anniversary of a U.N.-brokered cease-fire that ended the 2006 summer war between Israel and Hezbollah guerrillas.

Israeli Defense Minister Ehud Barak and other senior Israeli officials have warned in recent statements that Hezbollah has reinforced its arsenal in defiance of the U.N resolution that ended the 2006 war.

Israeli media reports claimed that Hezbollah acquired an anti-aircraft missile system to strike Israeli warplanes in the event of a new Israeli attack on Lebanon.

In turn, Nasrallah accused Israel of planning to assassinate Hezbollah leaders, saying this would not deter Hezbollah from continuing its battle against the Jewish state.

"I tell the Zionists: We don't fear you. Say whatever you want and do whatever you want. We know that you are planning new assassinations of resistance leaders. But this will not make us retreat," he said. "We are staying here and standing fast here."

In the past, Nasrallah has said Hezbollah possesses thousands of long-range missiles capable of hitting any area in Israel and that having these missiles was part of "a psychological war" against Israel.

The U.N. resolution that ended the 2006 war demanded Hezbollah disarm and banned arms shipments to the militants. But the guerrillas have refused to lay down their weapons, saying the arms are needed to defend Lebanon against Israeli threats.

The war erupted on July 12, 2006, when Hezbollah guerrillas crossed the border into Israel and attacked an Israeli patrol, killing three soldiers and capturing two. More than 1,000 Lebanese and 159 Israelis were killed before the fighting ended 34 days later.

In his speech Nasrallah, whose group is backed by Damascus and Tehran, also praised two key agreements this week between Lebanon and Syria — the establishment of diplomatic relations and the deal to start demarcating the contested border between the two long-estranged neighbors.

Nasrallah said the developments ushered in "a new phase and signals a qualitative development" in Lebanon-Syria relations.