Why did the Soviets develop the atomic bomb? They felt threatened by the US. They wanted to deter an American attack. Why does Hezbollah rearm? For the Same reason Israel does, deterrence. They want to assure they are not invaded again or bombed into the stone age again with impunity. Why does Israel drop 5 for 1 explosives on Gaza? You guys call it deterrence. Not everybody in the world believes in the same things. Some military powers frighten other people and the other people don't feel assured of benign intent by those with overwhelming firepower, especially once it's been used on them.
U.S., allies conduct 31 air strikes in Syria and Iraq against ISIS militants (Reuters)
from the article: Lebanon comes full circle back to the Syrian fold