By Feras Dalatey , Timour Azhari, Laila Bassam and Mahmoud HassanoDAMASCUS/BEIRUT, March 3 (Reuters) - Syria has reinforced its border with Lebanon with rocket units and thousands of troops, eight Syrian and Lebanese sources said on Tuesday, as conflict spread in the region including between Israel and Hezbollah in Lebanon.The sources included five Syrian military officers, a Syrian security official and two Lebanese security officials who spoke on condition of anonymity.