DAMASCUS, Syria – Syrian troops stepped up an offensive against rebels in the north on Wednesday, following explosions targeting security forces and a university campus that killed more than 100 people in two days.

Powerful suicide car bombs that killed about two dozen people in Idlib marked another escalation in the fight for control of northern Syria, a key battlefield in the country's civil war. The day before, massive blasts heavily damaged the main university in the commercial hub of Aleppo, killing 87 people and wounding scores of others.

The nearly simultaneous bombings in Idlib Wednesday bore the trademarks of Islamic militants, the most organized rebel fighters trying to topple President Bashar Assad's government. More than 60,000 people have been killed in the 22-month conflict, according to the United Nations.