WASHINGTON — The Obama administration has concluded it is not legally required to determine whether the Egyptian military engineered a coup d’état in ousting President Mohamed Morsi, a senior administration official said Thursday, a finding that will allow it to continue to funnel $1.5 billion in American aid to Egypt each year.

The legal opinion, submitted to the White House by lawyers from the State Department and other agencies, amounts to an escape hatch for President Obama and his advisers, who had concluded that cutting off financial assistance could destabilize Egypt at an already fragile moment and would pose a threat to neighbors like Israel.

The senior official did not describe the legal reasoning behind the finding, saying only, “The law does not require us to make a formal determination as to whether a coup took place, and it is not in our national interest to make such a determination.”

“We will not say it was a coup, we will not say it was not a coup, we will just not say,” the official said.