BEIRUT — France signaled Thursday that it was prepared to take part in enforcing a partial no-fly zone over Syria, piling pressure on President Bashar Assad’s embattled regime as it widens a major offensive against rebels in Damascus and surrounding areas.

French Defense Minister Jean-Yves Le Drian urged the international community to consider backing a no-fly zone over parts of Syria, but cautioned that closing the Arab nation’s entire air space would be tantamount to “going to war” and require a willing international coalition that does not yet exist.

He told France 24 television that Paris would participate in a full no-fly operation if it followed international legal principles.

But for now, he suggested that a partial closure – which U.S. Secretary of State Hillary Clinton said Washington was considering – should be studied.

Syria’s chief backer, Russia, meanwhile, said it was working closely with the Damascus government to ensure that its arsenal of chemical weapons stays under firm control and has won promises that it will not be used or moved.

In Syria, troops backed by tanks and helicopters broke into the Damascus suburb of Daraya, the scene of intense fighting over the last two days.

At least 18 people were killed.

Across the country, at least 100 people died Thursday in shelling and clashes, according to the Britain-based Syrian Observatory for Human Rights and the Local Coordination Committees.

The bloodshed coincided with the departure from the Syrian capital of the last of the United Nations military observers after their mission failed.