BEIRUT, Lebanon — President Bashar al-Assad of Syria displayed a new level of defiance on Thursday, warning Israel that he could permit attacks on the Golan Heights and suggesting that he had secured plenty of weapons from Russia — possibly including an advanced missile system — as his opponents faltered politically and Hezbollah fighters infused force into his military campaign to crush the Syrian insurgency.

Mr. Assad spoke in an interview broadcast on Al-Manar television, which is owned by his ally Hezbollah, the powerful Lebanese Shiite militant group, further punctuating his message of growing confidence that he could prevail over an insurgency that is now more than two years old and has claimed more than 80,000 lives.

Asked about Russian weapons deliveries, Mr. Assad said: “Russia is committed with Syria in implementing these contracts. What we agreed upon with Russia will be implemented, and part of it has been implemented over the recent period, and we are continuing to implement it.”

He was vague on whether Russia’s deliveries had included a sophisticated S-300 air missile system — of particular concern to Israel because it could compromise its ability to strike Syria from the air and because those missiles can hit deep inside Israeli territory. The Israelis have said they would not abide a Syrian deployment of S-300s, suggesting they would use force to destroy them.