The Islamic State terrorist group accused Israel of conducting multiple airstrikes against it in the northern Sinai peninsula, in a statement issued on its al-Amaq news agency Tuesday.

Earlier in the day, incoming rocket alert sirens sounded in southern Israel, as a result of a missile launched in Sinai. However, the projectile did not clear the border and landed within Egyptian territory.

According to the IS news agency, Israel carried out three strikes over the course of three days in the area of Sheikh Zuweid in the northern peninsula. The Israel Defense Forces would not respond to the allegation.

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In addition, Abdullah Kishta, a former senior member of Hamas who joined the Islamic State, was killed in Sinai, according to IS-affiliated media. But the circumstances of Kashta’s death were not immediately clear.

For the past two years, Kishta had reportedly worked as a bridge between the Islamic State and Hamas in the Gaza Strip, assisting in smuggling fighters in and out of the coastal enclave.

Israel’s Coordinator of Government Activities in the Territories Maj. Gen. Yoav Mordechai called Kishta out by name as a link between the two terrorist groups last year, saying the IDF had “proof” of the direct connection.

In July, a former Israeli senior official told Bloomberg news that Israel had carried out drone strikes against terrorists operating in the Sinai Peninsula in recent years.

The airstrikes were conducted with Egypt’s knowledge and blessing, according to the ex-official, who spoke to the US-based news site on condition of anonymity.

While it has become a well-known secret that Jerusalem and Cairo cooperate closely on security measures in the Sinai and Gaza, many of the details of that relationship have been kept a closely guarded secret.

Islamists in the restive Sinai who have since pledged allegiance to the Islamic State have waged an insurgency against Egyptian forces since the ouster of president Hosni Mubarak in 2011.

Fighting has intensified in recent years following a coup by current President Abdel-Fattah el-Sissi to remove Muslim Brotherhood-linked leader Mohammed Morsi from power.

Israeli military officials believe that despite ideological differences, Hamas in Gaza is cooperating with extremists affiliated with Islamic State or other armed groups in Egypt’s neighboring Sinai region.

They praise Egypt’s crackdown on Hamas’s cross-border smuggling tunnels, which had been a main conduit for weapons into Gaza, and say the Egyptian military is doing an admirable job in a fierce battle against IS militants in Sinai.

Israel has allowed Egypt to move heavy weapons like tanks, artillery and attack helicopters into the Sinai to fight extremists, overlooking provisions in the landmark 1979 peace treaty between the two countries.

The two sides also are considered to have close intelligence ties.

The two countries have entered something of a golden age in their relationship since Sissi assumed the country’s leadership in 2013.

“This is one of the best times we’ve ever had” in terms of cooperation between governments, Israeli ambassador to Cairo Haim Koren said earlier this year. “There’s good cooperation between the armies, we have understandings about the Sinai Peninsula, and basically, we see (eye-to-eye) on development of the region.”

The Associated Press contributed to this report.