National security correspondent Greg Miller discusses the impact of three terrorist attacks in France, Tunisia and Kuwait after an Islamic State leader called to make the month of Ramadan a time of "calamity for the infidels." (McKenna Ewen/The Washington Post)

A ghastly day of terror attacks on three continents began with a suicide bombing of a mosque in Kuwait. The attacker entered the Imam Sadiq mosque, one of the oldest Shiite mosques in Kuwait City, and detonated the explosives strapped to his body, killing at least 25 people and wounding hundreds.

The Islamic State, an extremist Sunni organization that views Shiites as apostate enemies, claimed responsibility for the attack, one of a spate of recent bombings of Shiite sites in the region. Footage of the suspected attacker approaching the mosque appeared on social media.

Other image-captures showed the attacker approaching the inner chamber of the mosque, where hundreds were gathered for Friday prayers.

According to accounts, he stood at the threshold of the room, and apparently shouted "God is great!" over the prayer service, as well as a declaration that that he would dine with the Prophet Muhammad in the evening.

Hassan Hassan, a Middle East scholar, summed up the barbarism of the act in this tweet: