NEW DELHI: The Islamic State has claimed responsibility for a deadly attack in Saudi Arabia, where a blast triggered by a suicide bomber killed 15 people at a mosque inside a special forces headquarters.

The blast took place in Abha, close to the Yemeni border. Twelve of the victims were members of a Special Weapons and Tactics (SWAT) unit, while three others were workers of the compound. Nine people were wounded in the attack.

The attack is the biggest Islamic State claimed attack targeting security workers in Saudi Arabia -- with the militant group recently gaining inroads into the oil rich kingdom. A spate of attacks in July were traced to the Islamic State, including a car bomb that exploded at a security checkpoint in Riyadh, and a policeman being gunned down during a raid in Taif where Islamic State flags were found.

Most significantly, the Islamic State claimed responsibility for two deadly attacks on Shia mosques in May. The attack on the Al-Anoud mosque in Dammam killed three people and wounded four others. The attack on a mosque in the village of al-Qadeeh killed ten people and injured over seventy others -- and was the first attack explicitly claimed by the Islamic State on Saudi soil.

The Islamic State has long targeted Saudi Arabia, with the group’s leader, Abu Bakr al-Baghdadi, in numerous videos and recordings, calling for attacks against the Saudi regime. In a video released last year, Baghdadi declared a target list for attacks in Saudi Arabia, without mentioning the country by name because it is a name derived from the ruling tribe, the al-Saud, whose authority IS does not accept. Baghdadi referred to Saudi Arabia as the “head of the snake and stronghold of disease.” The topmost position on the target list was accorded to Shias in Saudi Arabia. The leader urged supporters to “draw their swords” to fight and to kill Shiites, using the pejorative, sectarian term “rafidhah” for the sect.

At around the same time, a bombing in a small Shiite village in Saudi Arabia’s oil-rich Al Ahsa region in the east killed eight people was linked to the Islamic State. Authorities revealed that the leader of the attack was connected to IS militants, who received orders from abroad “specifying the target, the targeted, time of execution.” This is the first time, however, that the group has openly claimed an attack in Saudi Arabia.

The latest attack signals the aspirations of the group to expand out of Syria and Iraq. It has already established a foothold in conflict-torn Yemen, where a Saudi-led coalition is bombing Houthi rebels. The Islamic State has claimed a string of attacks on mosques in Yemen.

The group is also active in Tunisia, where it claimed an attack on tourists at the Bardo Museum in Tunis that killed 23 people.

It is also active in Libya, where in addition to a series of attacks on embassies in the Libyan capital of Tripoli, the group released a video purportedly showing the killing of up to 30 Ethiopian Christians and the beheading of 21 Egyptian Coptic Christians. The videos was released by the Islamic State’s media arm and was carried out by militants who say they are associated with the Tripoli Province of Islamic State -- a Libyan group that pledged allegiance to IS last year.

The beheading followed an attack on the luxurious Corinthia hotel in central Tripoli that killed nine people three weeks earlier that was claimed by the Islamic State. The militant group have also claimed other attacks -- including a series of attacks targeting empty embassies and local security buildings in Tripoli.

However, despite these attacks, it is not clear how much influence the group holds. For one, the Islamic State has seen success by capitalizing on the Shia-Sunni conflict in Iraq and Syria, and sectarian tensions of this scale do not exist in Libya. The crisis in Libya is more directly concerned with the local power vacuum, and this context has led to many on social media wondering whether the group is really responsible for all the attacks it has claimed.

Also recently, militant group Boko Haram that is based in Nigeria, pledged allegiance to the Islamic State. The group officially changed its name to Islamic State's West Africa Province," or ISWAP. Boko Haram -- itself a nickname for Jama'atu Ahlis Sunna Lidda'awati wal-Jihad, which in Arabic means "People Committed to the Propagation of the Prophet's Teachings and Jihad" -- had pledged allegiance to the Islamic State previously, but till now, was operating under its independent name. “Our caliph, God save him, has accepted the pledge of loyalty of our brothers of Boko Haram so we congratulate Muslims and our jihadi brothers in West Africa,” Reuters quoted Islamic State spokesman Abu Mohammad Adnani as saying in an audio message in March.

The group is also making inroads into South Asia, with reports emerging from Pakistan and Afghanistan indicating that IS militants are active in the region. 43 Ismaili Shia Muslims were killed and 20 others injured as Jundullah “Soldiers of Allah” that swore allegiance to the Islamic State last November struck in Karachi earlier this month. Jundullah spokesperson Ahmed Marwat told Reuters ,"These killed people were Ismaili and we consider them kafir (non-Muslim). We had four attackers. In the coming days we will attack Ismailis, Shi'ites and Christians." According to some reports, a blood-stained pamphlet was found at the scene in which the Islamic State itself had claimed responsibility.

Significantly, Jundullah had claimed last November that a delegation from the Islamic State had visited Balochistan. Marwat said then that the purpose of the visit was to see how it could work to unite Pakistani militant groups. This was just after Jundullah had announced it allegiance to IS. The military offensive against the militants has proven to be a double edged sword in Pakistan. On the one hand it has weakened and splintered the militant organisations, and on the other as a result of this has led them to seek new coalitions with the Islamic State clearly cashing in on the opportunity to enter both Pakistan and Afghanistan through the two outfits of the Taliban respectively, and their offshoots.

Earlier, the provincial government of Balochistan had conveyed a confidential report to the federal government and law enforcement agencies warning of increased footprints of IS, also known by the Arabic acronym Daish, in Pakistan.

In Afghanistan, the Islamic State claimed its first attack several weeks ago, when a suicide bomber detonated his explosives-laden vest outside a bank in Jalalabad, the capital of the eastern province of Nangahar, killing at least 34 people and injuring 125 others. The attack was claimed by a group called ISIS Wilayat Khorasan, with a statement issued naming the suicide bomber as Abu Mohammad Khorasani. A photograph purportedly of Khorasani was included, showing the attacker seated on a prayer mat, a scarf covering his face and a Kalashnikov rifle by his side. A black Islamic State flag was visible in the background.

These attacks indicate that the Islamic State has very much gained influence outside of its Syria and Iraq-based stronghold. This is a rare but very significant achievement for a militant group that’s expansion is usually curtailed by ideology, sects, societal differences and local opposing militias.