some of which were within visual range of the IDF, but did not take part in the fighting. The PLO retreated north of the Litani River, continuing to fire at the Israelis. The IDF used cluster bombs provided by the United States. According to U.S. President Jimmy Carter, this use of the cluster bombs violated the legal agreement between Israel and the U.S. because the weapons had been provided for defensive purposes against an attack on Israel. Israel also transferred American weapons to Saad Haddad's Lebanese militia, a violation of American law. Carter's administration prepared to notify Congress that American weapons were being used illegally, which would have resulted in military aid to Israel being cut off. The American consul in Jerusalem informed the Israeli government of their plans and, according to Carter, Prime Minister Begin said that the operation was over. UNSC Resolution 425 In response to the invasion, the UN Security Council adopted Resolution 425 and Resolution 426 calling for the withdrawal of Israeli forces from Lebanon were both adopted on 19 March 1978. The UN Interim Force in Lebanon (UNIFIL) was created to enforce this mandate, specifically "for the purpose of confirming the withdrawal of Israeli forces, restoring international peace and security and assisting the Government of Lebanon in ensuring the return of its effective authority in the area". UNIFIL forces arrived in Lebanon on 23 March 1978, setting up headquarters in Naqoura. Resolution 425 didn't result in an immediate end to hostilities. The Israelis continued military operations for 2 more days until they ordered a ceasefire. The PLO's initial reaction was that the resolution didn't apply to them because it didn't mention the PLO. The PLO leadership finally ordered a ceasefire on 28 March 1978, after a meeting between UNIFIL commander General Emmanual Erskine and Yasser Arafat in Beirut. Helena Cobban has described the agreement as "a turning-point in the history of the Palestinian resistance moment" because it was the first open acceptance of a ceasefire agreement with Israel that was endorsed by all official PLO bodies. Parts of the Palestinian resistance movement opposed the agreement and tried to violate the ceasefire. In April 1978, second-level Fatah leader Mohammad Daoud Oudeh (Abu Daoud) organized cells of about 70 to 80 fighters with the intention of breaking the ceasefire. Arafat and Khalil Wazir ordered the arrest of all involved and Abu Daoud was later accused of collaborating