109 American troops suffered traumatic brain injuries as a result of Iran's Jan. 8 missile attack on U.S. bases in Iraq, the Defense Department said in a statement Monday.

Why it matters: The development, first reported by Reuters, is a significant jump from the 50 cases the Pentagon disclosed in late January — and more than triple the number disclosed in the immediate aftermath of the strike.

Traumatic brain injuries are not always detected immediately, per the Centers for Disease Control and Prevention.

Pentagon spokesperson Thomas Campbell indicated in January that the numbers could increase.

Of the 109 troops diagnosed, 76 service members have returned to duty.

Yes, but: President Trump said that the injuries suffered by soldiers in the attack, which was a response to a U.S. strike that killed Iranian Gen. Qasem Soleimani, weren't very serious — and brushed them off as "headaches."

That comment prompted the Veterans of Foreign Wars, the nation's largest veterans group, to ask Trump to apologize for minimizing the injuries.

What they're saying:

"The Defense Department is steadfast in its efforts to deliver programs and services intended to lead to the best possible outcomes for our service members. We are grateful to the efforts of our medical professionals who have worked diligently to ensure the appropriate level of care for our service members, which has enabled nearly 70 percent of those diagnosed to return to duty. We must continue to address physical and mental health together.”

— Pentagon press secretary Alyssa Farah