Since October 10, ISIS and its sympathizers around the world have killed at least 525 people in six attacks in six countries outside its so-called caliphate.

American counterterrorism officials say that of the six attacks, three were directed by ISIS from its territory in Syria and Iraq and another two were so-called "announcement" attacks — local ISIS elements revealing their existence in dramatic fashion.

Full Coverage: San Bernardino Shooting Massacre

Though one of the two people who carried out the final attack, the massacre in San Bernandino, swore allegiance to ISIS, officials are still determining the extent of any relationship she and her husband might have had with the terror group.

Here is the chronology and body count of the attacks, with U.S. intelligence analysis of who was behind each:

—Oct. 10: The bombing of peace demonstrations outside the main train station in Ankara, Turkey left 102 dead. Directed by ISIS.

—Oct. 31: The bombing of a Metrojet plane bound for Russia over Egypt killed 224 passengers and crew. An "announcement" attack by the ISIS in the Sinai peninsula.

—Nov. 10: Two suicide bombers detonating themselves in a marketplace in southern Beirut, Lebanon, killing 43 people. Directed by ISIS.

—Nov. 13: Attacks on multiple sites in Paris, including the Bataclan theater, left 130 dead — excluding attackers. Directed by ISIS.

—Nov. 24: The bombing of a bus carrying members of the presidential guard in the Tunisian capital city of Tunis left at least 12 dead. An "announcement" attack by the ISIS affiliate in Tunisia.

—Dec. 2: The assault on a San Bernardino, California, office holiday party killed 14 people. Allegedly inspired by ISIS, but the extent of any contact between the shooters and ISIS or sympathizers is unknown.

Related: San Bernardino Shooters Were Radicalized for 'Quite Some Time'

A senior U.S. counterterrorism official confirmed that San Bernardino attacker Tashfeen Malik had indeed posted her allegiance to ISIS leader Abu Bakr al-Baghdadi on Facebook. He also noted that ISIS had praised the attack in a Saturday English language broadcast, calling the couple who carried it out “soldiers of the caliphate,” a term denoting members of the terrorist group’s army.

The official said there has also been at least one additional failed "announcement" attack. Three bombs exploded in Dhaka, Bangladesh, on Oct. 24 during a giant procession commemorating the Shiite Muslim holiday of Ashura. The explosions killed only one person.