MADRID—Bomb disposal experts defused a letter bomb at the U.S. Embassy in Madrid on Thursday, the sixth such device sent to high-profile targets in a wave that prompted Spain to step up security and vow not to be deterred from supporting Ukraine.
The campaign began with a package sent to Prime Minister Pedro Sanchez on Nov. 24, spurring Madrid to tighten security around public buildings. Since Wednesday, similar devices have also been sent to the defense ministry, an air force base, a weapons manufacturer, and the Ukrainian embassy—where a security officer was slightly injured.
