A Syrian jet has flown 12 miles into Lebanon, firing missiles at the border town of Arsal, witnesses told Al Jazeera.
There are no reports of casualties but this is the first time a Syrian plane has fired on the town in the Bekaa valley.
Lebanon has officially maintained a policy of "dissociation" regarding the Syrian war, but violence has spilled over the border in recent months with deadly clashes in Tripoli in March.
The last time a Syrian jet fired on Lebanese territory, President Michael Sleiman called the attack an "unacceptable violation" of Lebanese sovereignty.
Located in the Bekaa valley close to the Syrian border, Arsal residents have been broadly critical of the Assad regime throughout the Syrian conflict.