The United States has launched cruise missile strikes on an airbase in Syria, US officials said on Thursday, responding to a deadly poison gas attack that Washington has blamed on Syrian President Bashar al-Assad’s forces.

One of the officials said more than 50 Tomahawk cruise missiles were fired from US Navy destroyers in the eastern Mediterranean against several targets on the “Shayrat” base.

The operation appeared to have already been completed, a second official said.