BEIRUT - Hezbollah's increasingly visible support for Syrian President Bashar Assad and its latest military challenge to Israel has put the terrorist group on a collision course with domestic opponents who accuse it of dragging Lebanon towards regional conflict.While still denying it has sent forces to Syria to fight alongside soldiers trying to crush a 19-month-old uprising against Assad, Hezbollah has held a number of public funerals this month for fighters killed performing "jihadi duties."Security sources said the men were killed on Syrian territory.Hezbollah's political opponents, who have for months accused it of aiding Assad's forces, have rushed to condemn the group and warned its involvement in Syria could ignite sectarian tension within Lebanon where religious factions fought a 1975-1990 civil war.In a defiant speech on Thursday night, Hezbollah Secretary-General Sayyed Hassan Nasrallah said the Shi'ite group was not reinforcing its ally in Damascus. But his comments suggested that Hezbollah fighters may have been fighting in border regions of the poorly defined frontier.He also confirmed that Hezbollah had sent a reconnaissance drone deep into Israeli airspace, further escalating tensions with Israel which has threatened to bomb Hezbollah's patron Iran over Tehran's nuclear program.Nasrallah's speech was "aggressive towards all of his opponents in the Arab world, inside Lebanon and Israel", said Nabil Boumonsef, a columnist at the Lebanese newspaper An-Nahar. "He has put Lebanon and all of us in the eye of the storm," he said, reflecting growing criticism of a group which six years ago was lionized across the Arab world for standing up to Israeli military might in a 34-day conflict.Hezbollah, Boumonsef said, "will pay the price of this - and also Lebanon as it will deepen the division and fragmentation."The revolt against Assad has turned into a civil war with sectarian dimensions, largely pitting the majority Sunni Muslims against Assad's minority Alawite community, which is an offshoot of Shi'ite Islam.Tensions between Sunnis and Shi'ites have been rumbling in Lebanon ever since the end of the civil war, but resurfaced when former Prime Minister Rafik al-Hariri, a Sunni, was killed in 2005. Hariri supporters accused Syria and then Hezbollah of killing him - a charge they both deny. An international tribunal accused several Hezbollah members of involvement in the murder.But now the sectarian differences which Hezbollah was able to bridge when it played the role of resistance movement against Israel have deepened with its support for Assad.