US Defence Secretary Ashton Carter is beginning a tour of the Middle East, as part of efforts to ease fears over the recent nuclear deal with Iran.
On Sunday, he will meet officials in Israel, one of the strongest critics of the deal.
Mr Carter then travels to Saudi Arabia, Iran’s main regional rival.
Last Wednesday, world powers reached agreement with Iran on limiting Iranian nuclear activity in return for the lifting of sanctions.
The Israeli Prime Minister, Benjamin Netanyahu, called the deal an “historic mistake” which would only make it easier for Iran to back its proxies in the Middle East.
That position may have hardened after Iran’s supreme leader Ayatollah Ali Khamenei said his country would continue its support for the people of Palestine, Yemen, Syria, Iraq, Bahrain and Lebanon after the deal.
The Israeli Defence Minister Moshe Yaalon, hinted his country could ask for increased US military aid as a counterweight to the accord.
Saudi Arabia has officially said it supports the deal, although it is also thought to have similar concerns to Israel that the agreement legitimises Iran.
Mr Carter is due to visit Jordan as well, for talks on the strategy for tackling the Islamic State militant group.