In a televised address, Hezbollah leader Hasan Nasrallah defended the Lebanese group’s decision to send fighters to Syria to support President Bashar al-Assad. (AFP/Getty Images)

Hezbollah’s leader delivered a defiant speech Tuesday that sought to dispel any notion that his Lebanese Shiite group is strained by its intervention in Syria, warning that it could still confront Sunni extremists and Israel.

In a televised address marking the annual Shiite Ashura observance, Hasan Nasrallah defended the decision about two years ago to deploy thousands of Hezbollah fighters to bolster the regime of Syrian President Bashar al-Assad.

Nasrallah described Hezbollah’s role in the three-year-old Syrian civil war as “a great victory,” but the intervention has angered many in the Arab world, especially Lebanon’s Sunnis, who support Assad’s largely Sunni opponents.

Hezbollah’s forces have suffered hundreds of battlefield deaths in Syria, but Nasrallah, speaking to Shiite worshipers in Lebanon and audiences across the region, said the group is “stronger than before” and has gained serious wartime “experience.”

“The whole world was in agreement” that the Syrian government would fall “within months,” he said. “However, nearly four years have passed, and Damascus is still firm.”

He also warned that Hezbollah could still deal devastating blows to longtime foe Israel. Israel and Hezbollah fought a 34-day war in 2006 that destroyed swaths of Lebanon.

Nasrallah warned Israelis to “close your airports, your ports” if fighting should erupt, because all of Israel is within range of Hezbollah rockets.

The remarks came amid heightened tension in Lebanon stemming partly from Hezbollah’s presence in Syria, which critics say has worsened sectarian relations in Lebanon.

The group has struggled to keep the Syria war from spilling into Lebanon. Sunni militants with links to extremists in Syria and possibly Iraq have carried out a growing number of attacks in Lebanon, including a revolt last month in the northern city of Tripoli that the military put down.

Shiite areas in Beirut and other parts of Lebanon were placed on virtual lockdown Tuesday for Ashura ceremonies, which commemorate the killing of Imam Hussein, the prophet Muhammad’s grandson, in the 7th century. The Sunni-Shiite schism emerged from that event.

In his address, Nasrallah issued a special warning to “takfiris,” or extremist Sunnis such as Islamic State militants, who have captured parts of Syria and Iraq and may have designs on Lebanon.

“They will be defeated,” he said, “and we will have the honor of defeating them.”

Last year, Sunni militants operating along Lebanon’s border with Syria started targeting Hezbollah strongholds with suicide attacks and car bombings.

With Hezbollah fighters focused on Syria, Lebanon’s military has assumed a more prominent role in securing stability at home.

On Tuesday, France and Saudi Arabia signed a $3 billion contract to provide Lebanon’s army with weapons.