WASHINGTON—The Pentagon is removing U.S. missile systems from the Middle East next month, U.S. military officials said, a move that will leave American allies with fewer defenses as the White House ramps up its rhetoric against what it says are threats posed by Iran.

Defense Secretary Jim Mattis is pulling four Patriot missile systems out of Jordan, Kuwait and Bahrain next month in a realignment of forces and capabilities as the military steps up its focus on threats from China and Russia, according to multiple senior military officials.

The relocation of the systems out of the Middle East, which hasn't been previously disclosed, is one of the most tangible signs of the Pentagon's new focus on threats from Russia and China and away from the long-running conflicts in the Middle East and Afghanistan.

Two Patriot missile systems will be redeployed from Kuwait, and one each from Jordan and Bahrain, officials said. Patriots are mobile missile systems capable of shooting down missiles and planes.

The four systems have been taken offline and will be redeployed by next month, officials said. There are no plans for any of them to be replaced, and they are being returned to the U.S. for refurbishing and upgrades, an official said.

Although some Patriot systems will remain in the region, officials said the removal of the four batteries amounts to a major drawdown of the capability Patriots provide in the region.

The missile systems have been used for mostly defensive purposes, to protect not only U.S. bases and installations in those countries but also as an effective defense for allies. Their removal comes as the White House intensifies its rhetoric against Iran and amid an increasingly complex battlefield in Syria.

The State Department on Tuesday issued a 48-page report that detailed threats posed by Iran, including its missile programs. The report said Iran maintains "a stockpile of hundreds of missiles that threaten its neighbors in the region."