Egyptian Army spokesperson Col. Ta'amar Afrahi told a Cairo newspaper that Egypt alone was responsible for the security of Sinai, and was fighting terrorism there without the help of any other country.
In the wake of that attack, however, Israel chose to enter the fray, The New York Times reported over the weekend.
The airstrikes are being conducted with Egyptian President Abdel Fattah el-Sisi's approval, The Times added.
Desperation to try to keep the ISIS affiliate in the Sinai Peninsula in check saw Israeli warplanes, drones, and attack helicopters given secret permission by the Egyptian junta to carry out over 100 operations in the peninsula over the past two years, according to media reports.
"Once enemies in three wars, then antagonists in an uneasy peace, Egypt and Israel are now secret allies in a covert war against a common foe", the Times said.
While security coordination between Jerusalem and Cairo is known to be close, the ties are still unpopular in Egypt, despite almost three decades of peace.
At the meeting, The New York Times reported, Kerry proposed a regional agreement in which Egypt and Jordan would guarantee Israel's security as part of a deal for a Palestinian state. The Israeli drones are unmarked, and the Israeli jets and helicopters cover up their markings.
The New York Times described the countries' collaboration in north Sinai as "the most dramatic evidence yet" of the geopolitical changes taking place in the region.
The report noted that Israel had also complained to the US that Egypt was not upholding its end of the deal in North Sinai.
American officials say Israel's air campaign has played a decisive role in enabling the Egyptian armed forces to gain an upper hand against the militants. While militancy has taken a considerable toll on security forces and civilians in Sinai, the militants have never been known to use Egypt as a base for attacks on Israeli targets.