The US Defence Department announced on Friday that it would include close ally Israel in the area covered by its Middle East-focused Central Command.
In another sign of the rapprochement brokered by President Donald Trump between Israel and Arab countries, the Pentagon said US military dealings with Israel would no longer be handled by its European Command.
"We structure boundaries to best mitigate risk and protect US interests and partners," the Pentagon said in a statement.
"The easing of tensions between Israel and its Arab neighbours subsequent to the Abraham Accords has provided a strategic opportunity for the United States to align key partners against shared threats in the Middle East."
That was mainly a reference to Iran, which the US, Israel and Arab countries view as the leading security threat to the region.
For decades at odds with its Arab neighbours over its treatment of Palestinians, Israel has over the past year broken barriers on open co-operation and communications with Gulf countries under the Trump-fostered Abraham Accords.
Moving Israel under the Central Command potentially makes security co-operation with the United States on regional matters easier, and could bring Israeli military officials in closer proximity to those of Gulf neighbours.
But it could also complicate Centcom co-operation with Iran allies like Iraq, where the US retains 2,500 troops.
"Israel is a leading strategic partner for the United States, and this will open up additional opportunities for co-operation with our US Central Command partners, while maintaining strong co-operation between Israel and our European allies," the Pentagon said.