KFAR TAPUAH, West Bank  Thirty Israeli couples are on a waiting list to move into the Kfar Tapuah settlement, which teems with children on the hilltops south of Nablus. Some on the list grew up here. But there is not an apartment available for sale or rent, or even a stifling trailer to be had.

If Israel built all the housing units already approved in the nation’s overall master plan for settlements, it would almost double the number of settler homes in the West Bank, according to unpublished official data provided to The New York Times.

The decision of whether to build, and how much, goes to the heart of the tensions between the administrations of Prime Minister Benjamin Netanyahu of Israel and President Obama, an unaccustomed and no-budge conflict between Israel and the United States. Washington is standing firm against any additional settlement construction in the West Bank, including what Israel argues is necessary to accommodate what it terms “natural growth.”

That term has been defined vaguely by Israeli officials, meaning for some that settlements should expand to accommodate only their own children. But Mr. Netanyahu, of the conservative Likud Party, made his own wider position clear on Monday. He said that while Israel would not allow new settlements and that some small outposts would be removed, building within the confines of established settlements should go on.