“As we have said before, the United States supports Palestinian reconciliation on terms which promote the cause of peace,” Tommy Vietor, a spokesman for the National Security Council, said in the administration’s only public response. “Hamas, however, is a terrorist organization which targets civilians.”

He added that any Palestinian government had to accept certain principles announced by international negotiators known as the Quartet: the United Nations, the European Union, the United States and Russia. They include renouncing violence, abiding by past agreements with the Israelis and recognizing Israel’s right to exist. Hamas has never agreed to those conditions.

Administration officials declined to discuss publicly the impact the reconciliation might have on American policy, saying they were still trying to learn more about how exactly the two rival organizations would be able to reunite years after violently splitting.