Some components of a powerful antiship missile system have already been moved to Lebanon, according to previously undisclosed intelligence, while other systems that could target Israeli aircraft, ships and bases are being stored in expanded weapons depots under Hezbollah control in Syria, say current and former U.S. officials.

Such guided weapons would be a major step up from the “dumb” rockets and missiles Hezbollah now has stockpiled, and could sharply increase the group’s ability to deter Israel in any potential new battle, officials say.

The movements appear to serve two purposes.

Iran wants to upgrade Hezbollah’s arsenal to deter future Israeli strikes—either on Lebanon or on Iran’s nuclear program, U.S. and Israeli officials say. In addition, these officials said they believe the transfers were meant to induce Hezbollah to commit to protect Syrian President Bashar al-Assad as well as supply lines used by both his regime and Hezbollah.