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The Pentagon on Tuesday announced that it is sending another 300 troops to the Middle East.
Pentagon press secretary Brig Gen Pat Ryder said the troops would be moving from bases in the US and would go to the area covered by Central Command, but not to Israel.
The Pentagon had previously said it was sending 900 troops to the Middle East as regional tensions soar.
“These additional troops will provide capabilities and explosive ordnance disposal, communications and other support enablers for forces already in the region,” Brig Gen Ryder said.
“They are intended to support regional deterrence efforts and further bolster US force protection capabilities.”
The US is moving to increase its military presence across the Middle East to protect American and partner forces, and try to stop the Israel-Gaza war becoming a regional war.
Many of the troops being sent are operators for Patriot and Terminal High Altitude Area Defence, or Thaad, missile systems.
The Pentagon says its anti-ISIS forces based in Iraq and Syria have been repeatedly attacked by Iran-backed militias.
Brig Gen Ryder said that since October 17, there have been 27 attacks on US forces, 11 in Syria and 16 in Iraq.
October 17 is the same day Al Ahli Arab Hospital in the centre of Gaza city was hit by a devastating blast.
Israel has denied responsibility and blamed a failed Hamas rocket attack.