Lebanese refugees and Syrian militants board buses crossing the border from Lebanon into Syria. They are headed for Idlib in the northwest, a rebel-held area.Seeing them off: Hezbollah fighters and personnel.Shi'ite Hezbollah routed the Sunni Islamist Nusra Front in the mountains around Arsal last week. This area is their last foothold on the frontier.Some 7,000 Syrians, a thousand of them militants, are to be evacuated under a deal that echoes those struck in Syria between the government and rebels.Those deals have helped Syrian President Bashar Assad recapture rebel areas. Critics say they amount to forcible transfer of populations sympathetic to the opposition.Hezbollah's role in helping Assad defeat his opponents along the Lebanese-Syrian border has been highlighted in Arsal. Three years ago, the town witnessed one of the most serious spillovers of Syria's six-year civil war into Lebanon.Then, militants from the Nusra Front - at the time linked to Al-Qaida - and Islamic State briefly overran the town.They abducted dozens of Lebanese soldiers and policeman. Nine remained in Islamic State captivity. Their fate is unknown.