CAIRO — (CNN) The Islamic State in Iraq and Syria earned its brutal reputation as it spread violence and terror across those two war-torn countries.

But in an apparent expansion of its reach, it has, in just the past week, claimed responsibility for a roll call of attacks in other countries: the deadly bombing of a mosque in Kuwait last Friday, the horrific beachfront killings in Tunisia the same day and now coordinated military attacks in Egypt.

ISIS apparently launched simultaneous attacks Wednesday on Egyptian military checkpoints, reportedly killing 17 Egyptian soldiers and injuring 30 others.

The wave of violence comes after a spokesman for the Sunni extremist group urged followers to step up attacks during the Muslim holy month of Ramadan.

And it shows how ISIS’ tentacles are reaching out from Yemen on the southern tip of the Arabian Peninsula across the Gulf states to Tunisia in North Africa.

ISIS claimed responsibility for Wednesday’s attacks in the restive Sinai province in statements posted on Twitter.

The confrontations between ISIS militants and Egyptian troops left at least 100 jihadis dead, the Egyptian military reported on its official Facebook page Wednesday.

Egyptian military spokesman Brig. Gen. Mohamed Samir told CNN Thursday that the situation in the Sinai was now “100% under control.” He also said that the Muslim Brotherhood — banned as a terrorist organization in Egypt — was “behind all of this.”

Security officials and observers in Egypt have described the apparently coordinated attacks in the northern Sinai as unprecedented.

The Egyptian military said at least 300 militants launched the offensive, using car bombs and different kinds of weapons.

The ISIS-affiliated State of Sinai group claimed it attacked more than 15 checkpoints and had used at least three suicide bombers.

The assault was focused on a town close to the Gaza border, with residents there caught in the crossfire.

The coordinated attack has raised concerns of a new chapter in an insurgency that the Egyptian military has been struggling to contain in the Sinai for the past couple of years.

The Sinai borders the Mediterranean Sea to the north and Israel to the east. It is the only part of Egypt that lies in Asia rather than Africa.

ISIS has said it’s behind the bloody attack on foreign tourists in the Tunisian coastal town of Sousse in which 38 people died.

Thirty of the people killed in the massacre at a beachfront hotel last week are UK citizens, authorities said Thursday, marking the worst terror attack against Britons in a decade.

The gunman responsible trained with the people who carried out an attack on the Bardo Museum in Tunis in March, Tunisian authorities said. ISIS has also claimed responsibility for that attack.

Twenty-seven worshippers lost their lives and more than 200 were injured when a bomb ripped through the Shia-affiliated Al-Sadiq mosque during Friday prayers. ISIS claimed responsibility for what was the worst terror attack Kuwait has seen in many years.

Authorities say they’ve arrested a number of suspects.

But beyond the immediate manhunt looms the issue of preventing such attacks in the future and ensuring that ISIS, which is wreaking havoc in neighboring Iraq, doesn’t do the same in Kuwait.

The choice of target is significant, CNN terrorism analyst Paul Cruickshank said, because the group has been trying to increase sectarian tensions by provoking Shia reprisals against Sunnis.

It also wants to force Gulf states to protect Shia minorities and by forcing them into uncomfortable political situations, to de-legitimize those regimes, he added.

ISIS has claimed responsibility for a number of bombings in the Yemeni capital, Sanaa, in the past month. One this week targeted a group of mourners, including women and children, while others have targeted mosques associated with the Shiite Houthis.

Yemen has for months been torn by fighting between the rebel Houthi militiamen and government forces loyal to President Abdu Rabu Mansour Hadi, who fled Sanaa in March as the Houthis seized control of the city.

A coalition led by Saudi Arabia has launched airstrikes against the Houthi rebels in a bid to counteract what it sees as Iranian influence in the region. Shia-majority Iran denies supporting the Houthi rebels.

ISIS claimed to be behind two mosque attacks in Saudi Arabia in May, the first on the Imam Ali mosque in the village of Qudayh and the second on the Imam Hussein mosque in a predominantly Shiite neighborhood of Dammam, a coastal city.

Dammam is one of the few Shiite population centers in a country in which 85% to 90% of citizens are Sunni, the other major Islamic sect.

Since storming Mosul just over a year ago and declaring an Islamic caliphate across parts of Syria and Iraq, ISIS has extended its reach across a swath of the embattled country.

Despite the efforts of Iraq’s armed forces and Kurdish Peshmerga fighters, backed by daily airstrikes from a U.S.-led international coalition, the Sunni extremists continue to control vast areas and commit new atrocities.

A major blow came in May, when Iraqi security forces lost the key city of Ramadi in the western province of Anbar to ISIS.

Syria, gripped by conflict for more than four years, has been the heartland for ISIS’ fighters, with the city of Raqqa their self-declared capital.

Kurdish forces in the north of the country, along with Syrian opposition groups in the south, have made some recent gains against ISIS. But ISIS has been quick to strike back elsewhere and experts say its withdrawals in some places may be strategic, rather than a sign it is weakening.

ISIS first established a stronghold around Derna in the east of the country last fall. Since then, it has expanded its reach to Sirte, the final major stronghold of Moammar Gadhafi loyalists in the Libyan civil war.

In April, ISIS claimed to have executed two groups of prisoners, believed to be Ethiopian Christians, in two locations in Libya.

That came two months after the extremist group released a video of 21 Coptic Christians from Egypt being executed on a Libyan beach.

It’s also attacked the Libyan military in the south of the country.

Analysts worry that ISIS’ growing presence, coupled with the country’s lack of government and porous borders, make it a particular threat to regional stability.

Tunisian authorities have said it’s likely the Sousse gunman had a connection to a Libyan terrorist organization and spent time in Libya.

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