Five U.S. Army Special Operations troops died in a refueling "mishap" with a helicopter over the eastern Mediterranean Sea, defense officials said Sunday, in an incident that U.S. officials have handled with extra care as the Biden administration attempts to keep the war in Gaza from expanding throughout the region.

Two U.S. officials, speaking on the condition of anonymity because of the sensitivity of the issue, said the troops were in the region as part of the Pentagon's broader contingency planning for the war, which includes preparing for potential evacuations of U.S. citizens out of Israel and Lebanon. The helicopter went down off the coast of southeastern Cyprus, according to one of the officials and warnings to aviators published Saturday while a search-and-rescue operation, now concluded, was underway. U.S. officials identified the helicopter that went down as an MH-60, a variant of the Black Hawk helicopter that is flown by the elite 160th Special Operations Aviation Regiment.

U.S. European Command, which oversees military operations in the area, first disclosed the incident Saturday, though it did not clarify which branch of the military or what kind of aircraft was involved. The New York Times first reported the affiliation of the service members killed on Sunday.

"Out of respect for the families affected, we will not release further information on the personnel involved at this time," a Saturday statement said. "The cause of the training incident is currently under investigation. However, we can definitively say that the aircraft sortie was purely related to training and there are no indications of hostile activity."

In a statement to The Washington Post on Sunday, EUCOM officials said they would not be releasing information about the type of aircraft or any details about the personnel involved in the crash until 24 hours after it had notified next of kin. The statement added that the aircraft crashed after "a mishap during routine air refueling training."

The Pentagon has surged forces into the region as a show of force, and a demonstration of solidarity with Israel, designed to discourage adversaries such as Iran from further inflaming tensions. As part of that effort, the United States has deployed two aircraft carrier strike groups, each comprising about 7,500 troops.

It was not clear what role Cyprus may be playing in U.S. Special Operations in the region. U.S. relations with the island country have been expanding, with the Biden administration last year lifting a decades-old arms embargo.

Defense Secretary Lloyd J. Austin said in a statement Sunday that he and the Pentagon "mourn the tragic loss of five U.S. service members."

"We will remember their service and their sacrifice," he said.

President Biden said he and first lady Jill Biden were "praying for the families and friends who have lost a precious loved one - a piece of their soul."

"Our entire nation shares their grief," Biden said in a statement that highlighted the fact that it is Veterans Day weekend. "When we pause to honor our nation's veterans, we once more affirm the sacred obligation we bear to those who volunteer to serve our nation as well as their families, caregivers, and survivors. We pray for the families of all our fallen warriors today and every day."

It was not clear if the helicopter collided with a tanker plane during the incident, but mishaps involving refueling occur on occasion. The procedure requires connecting a rigid tube extending from the front of the helicopter to the tanker.

The Army has suffered several aerial collisions with helicopters this year.

In March, nine service members were killed after two Black Hawk helicopters crashed in southern Kentucky during routine training practice, according to army officials. A few weeks later, two Army Apaches collided near Healy, Alaska, killing three soldiers and gravely injuring a fourth. The aircraft were headed to Fort Wainwright, returning from training at the time of the crash.

The fatal crashes prompted the U.S. Army to ground all aviation units, except those conducting critical missions, until they completed safety training.

A March report by the U.S. Government Accountability Office published, which gathered data by the Army and Air National Guard, found that 298 helicopter accidents took place during noncombat flight operations from fiscal years 2012 through 2021. Approximately 45 of those were considered serious helicopter accidents, which involved "death, permanent disability, extensive hospitalization," took place over time and were mainly a result of human errors, the report found.