This "problem" about building in East Jerusalem is more Arab Propoganda. The US is more worried about that than if Iran builds nuclear weapons. In 1947, the Arabs rejected a plan that would make Jerusalem an international city. They took over the eastern half in 1948. Then they lost it when Jordan attacked Israel in 1967. It is legally part of Israel. The US has no right to tell any country where it can build or not build in its capital. No one objects when the US builds in Washington, DC. That was stolen from the Native American Indians anyway.
U.S. to defend Syrian rebels with airpower, including from Assad (Reuters)
from the article: Netanyahu: Probe events that led to row with U.S. over East Jerusalem