The militant group said 16 of its members were killed in Friday’s attack in Beirut, which Lebanon’s health minister said left a total of 31 people dead.

The Hezbollah commander killed in an Israeli airstrike in Beirut’s southern suburbs was one of the Lebanese militant group’s top military officials.

The absence of a full-blown war in Lebanon has been touted as a core U.S. achievement, but now Washington’s grip on the crisis appears more tenuous than ever.

In both cases the devices were used by members of Hizbullah, the Shia militia that has fired rockets at Israel for almost a year. Some 20 people were killed and 450 injured in the latest attack, on top of at least 12 killed and nearly 3,

Israel is attempting a risky strategy, increasing the intensity of its attacks in an attempt to force Hezbollah to back down, while raising the chances of an aggressive response that devolves into a land war.

The strike in Beirut extended a string of Israeli attacks that have injured thousands and left U.S. and regional officials worried about a wider conflict.