Iran will likely respond pragmatically to the fall of Syrian President Bashar al Assad's regime by seeking talks with the United States and regional allies, but the weakening of its regional proxy network will likely also make Tehran more willing to pursue nuclear weapons to bolster its security. The Dec. 6 fall of the Assad government is the latest major blow to Iran's so-called ''Axis of Resistance'' deterrence strategy against Israel and the United States, following Israel's decimation of Hamas in Gaza and its significant degradation of Hezbollah in Lebanon. The Syrian rebel group Hayat Tahrir al-Sham, or HTS, and its allies' seizure of Syria is particularly problematic for Tehran because it severs the land corridor between Iran and Lebanon, making it far more difficult for Iran to send weapons and fighters to Lebanon to support Hezbollah and help rebuild the Shiite militia's capabilities....