The United States flew a pair of B-52 strategic bombers from a base in Louisiana to the Middle East on Thursday as a show of force against Iran, underscoring the U.S. military’s ability to defend itself and its allies in the region as tensions between Tehran and Washington escalate during the final days of the Trump administration.

The B-52H “Stratofortresses,” long-range heavy bombers that can carry nuclear warheads or perform conventional missions, left Barksdale Air Force Base on a short-notice nonstop mission.

U.S. Central Command, which oversees the Middle East, said the mission was designed to demonstrate the U.S. military’s commitment to its regional partners and ability to deploy combat power rapidly to anywhere in the world. It was the second such mission in two months.

“Potential adversaries should understand that no nation on earth is more ready and capable of rapidly deploying additional combat power in the face of any aggression,” Gen. Kenneth F. McKenzie Jr., Centcom commander, said in a statement.

McKenzie said the ability to fly strategic bombers “halfway across the world in a non-stop mission” and integrate them with the forces of other countries in the region demonstrates the U.S. military’s close working relationships and a “shared commitment to regional security and stability.”

The show of force comes at a time of heightened risk to the United States and its allies in the Middle East. The bomber mission took place a week after the U.S. government decided to withdraw some staff from its embassy in Iraq, where tension with Iranian-backed forces has persisted for months.

It also comes after the targeted killing late last month of Mohsen Fakhrizadeh, an Iranian nuclear scientist who U.S. officials believed was behind Iran’s previous efforts to covertly develop nuclear weapons. He was killed in an ambush east of Tehran that Iranian officials blamed on Israel.

As the first anniversary of the U.S. killing of senior Iranian military leader Qasem Soleimani approaches Jan. 3, the Trump administration faces the possibility that Iran or its proxies could hit back against Western targets in the region at a moment of transition in Washington.

The U.S. Senate on Wednesday failed to block a controversial $23 billion arms deal with the United Arab Emirates, which will send F-35 fighter jets and Reaper drones to the nation. The UAE has been involved in the Saudi Arabia-led intervention against Iranian-backed Houthi rebels in Yemen.

The B-52 mission also comes as President Trump withdraws more U.S. troops from Afghanistan and Iraq in a final push to get closer to upholding his promise to end U.S. involvement in those nations, creating a sensitive security situation for American forces.

Trump fired defense secretary Mark T. Esper in November and installed acting secretary Christopher C. Miller, who quickly announced plans to draw down to 2,500 troops in Afghanistan, a plan that Esper opposed.

“We are aware that Iran has increased its military activity through direct attacks and support to its proxies in the region,” a U.S. defense official said, speaking on the condition of anonymity to discuss the details of the mission. “We do not seek conflict with the regime in Iran. But we are prepared and postured with forces that span the full range of combat capability to deter further unwarranted aggression and preserve the international rules-based order.”

The B-52 aircraft flew in the western portion of the Persian Gulf near Bahrain and Qatar, where they integrated with aircraft from the U.S. military and those of partner nations, before returning into Saudi Arabian airspace as they exited out of the theater, the defense official said.

Despite the increased activity by Iran, the defense official said the flights weren’t a direct response to specific actions taken by any specific nation but rather part of a broader demonstration of U.S. resolve.

U.S. Strategic Command, which oversees the U.S. nuclear force, has been conducting such missions since 2014, the official said.