The Biden administration is boosting the United States' military presence in the Middle East.
The Pentagon says the increased show of force will deter Iran and its proxies from escalating the conflict in Israel, which has turned the region into a cauldron of tensions.
Biden's Defense Secretary Lloyd Austin said he gave "prepare to deploy orders" to an "additional number of forces."
In addition, Terminal High Altitude Area Defense (THAAD) and Patriot missile systems have been sent to the region, and two carrier strike groups have been sent to the Eastern Mediterranean.
Austin said he made the preparations after discussions with President Biden, who visited Israel last week to show his support for the country following the deadliest attack on Jews since the Holocaust.
"These steps will bolster regional deterrence efforts, increase force protection for U.S. forces in the region, and assist in the defense of Israel," Austin said.
Austin said he would "continue to assess our force posture requirements in the region and consider deploying additional capabilities as necessary."
There are fears that Hezbollah, the Iran-backed Islamist group that operates in Lebanon, could open another front north of Israel. Incidentally, Monday marked the fortieth anniversary of the deadly Beirut barracks attack that killed over 200 U.S. Marines.
Iranian proxies in Iraq targeted American bases last week in a rocket attack that injured some troops.
President Biden has asked Congress for another $100 billion to support Israel and Ukraine following a trip to Israel last week. Biden has resisted calls from his left for a cease-fire, saying Israel has a right to respond to Hamas' brutal terror.
Israel has been bombing Gaza, which Hamas controls, for days ahead of an anticipated ground invasion. So far, Biden has pledged not to put American boots on the ground.
However, the Pentagon's mobilization is likely to raise fears of further U.S. entanglement in the volatile region, which the U.S. spent years bogged down in following the 2003 invasion of Iraq.
"If any group or any country is looking to widen this conflict and take advantage of this very unfortunate situation that we see, our advice is: don't," Austin told ABC News.
"We maintain the right to defend ourselves and we won't hesitate to take the appropriate action," he added.