A diplomatic deal between the United States and Iran could still avoid a military confrontation.
But one of Washington's largest-ever military buildups in the Persian Gulf is rapidly taking shape.
Experts say the deployment is aimed at giving US President Donald Trump military options if he chooses to act on his threats to attack Tehran for failing to make a nuclear deal and crack down on protesters.
Iranian security forces killed thousands of demonstrators in January, after protests erupted in late December 2025 over the sharp collapse of the Iranian currency.
“The gathering of forces is a point of pressure applied by the United States on Iran to come to a negotiated agreement,” said Amin Tarzi, professor of strategic studies at Marine Corps War College.
He said that after the buildup, the US military posture in the Gulf is “robust” with “naval and defensive air defense capabilities, plus offensive air components.”
He said that in terms of numbers, the US buildup might not be the largest in the region where Washington has fought some of its most recent foreign wars.
Hundreds of thousands of American troops participated in two major US-led operations against Iraq: the 1991 Persian Gulf War, which liberated Kuwait from Iraqi occupation, and the 2003 invasion of Iraq, which toppled Saddam Hussein's regime.
“The nature of war has changed dramatically, even compared to 2003,” Tarzi said. “These are assets that have more capability but a much smaller footprint.
'Massive Armada'
In late January, President Trump reiterated his call for Tehran to face a “far worse” attack than the one aimed at the country in June if it fails to make a deal over its nuclear program.
He said a “massive armada” was heading to Iran and it was able to “rapidly fulfill its mission, with speed and violence”.
The fleet is led by the aircraft carrier USS Abraham Lincoln, supported by several advanced warships that together form a carrier strike group. Last week, one of the strike group's jets shot down an Iranian drone.
David Des Roches, a professor at Washington’s Thayer Marshall Institute, said multi-role ships such as USS Delbert D. Black, USS Mitscher, and USS McFaul are already in the Persian Gulf theater. All of these can launch missile strikes and have advanced naval and air defense capabilities.
On February 10, Trump said he might dispatch a second aircraft carrier strike group to the region to take part in the military action if talks with Iran fail.
Des Roches said the US forces currently around Iran are nimbler. “[The buildup] is much smaller, and it's much easier to scale up and scale down,” he said.
He said advances in US military capacity mean it is also possible that Washington can again use strategic B2 bombers just like it used in June 2025 to strike deep inside Iran.
“These can come from the United States or Diego Garcia,” he said. In the Indian Ocean island of Diego Garcia, the US shares a joint military base with the United Kingdom.
CENTCOM
The Gulf region is part of the US Central Command (CENTCOM) area of operations, where the oil-rich Sunni Arab monarchies of Saudi Arabia, the United Arab Emirates (UAE), Bahrain, Kuwait, Oman, and Qatar have hosted US army, air force, and naval bases. The region is now estimated to have up to 40,000 US troops.
The Al-Udeid air base in Qatar houses CENTCOM's forward headquarters. In June 2025, Iran attempted to target it in retaliation for the US air strikes on its nuclear facilities. The US Navy’s Fifth Fleet is based in Bahrain, from where it secures some of the world’s busiest shipping lanes in the Persian Gulf and Red Sea.
Additional US bases and ships are scattered in Jordan, the Red Sea, and the Mediterranean. In Iraq and Syria, the US military presence has mostly been aimed at counterterrorism operations against the Islamic State extremist group.
“The massive increase in naval presence, in air presence, in air defenses, does signal the United States is very serious,” said Brian Carter, the research manager at the Critical Threats Project at the American Enterprise Institute think tank in Washington.
He said that Washington is bringing in air defense platforms to help defend its bases and US allies from any Iranian attacks.
“The navy fits into that picture as well, because naval ships can be armed with surface-to-air interceptors to shoot down incoming missiles,” he said.
Across the Middle East, Washington has beefed up its air and missile defenses.
In recent weeks, it has deployed additional batteries of the Terminal High Altitude Area Defense (THAAD) and Patriot missile defense systems to the Gulf Arab nations and Jordan. Patriots are effective against low-flying and short-range projectiles. THAAD is designed to intercept ballistic missiles at high altitudes.
Carter says that, in contrast to Iran's weak defense capabilities, the US defensive capacity is quite strong because of investments during the past decade.
“That's a kind of important asymmetry that we should keep in mind as we're thinking about strikes going forward,” he said.
