Islamic State militants re-occupied Palmyra on Sunday, taking the ancient central city from government troops in a major advance after a year of setbacks in Syria and neighboring Iraq, a Syrian government official and the group said.

In retaking Palmyra, the extremist group appeared to be taking advantage of the Syrian and Russian preoccupation with Aleppo, timing its attack to coincide with a massive government offensive to capture the last remaining opposition-held neighborhoods in the northern city.

Palmyra, with its towering 2,000-year-old ruins, holds mostly symbolic meaning in the wider Syrian civil war, although its location in central Syria gives it some strategic significance as well. […]