Much of Tehran’s arsenal of missiles may be hidden underground, making it harder to destroy.
President Trump also declined to rule out sending ground troops into Iran as the conflict spread into the Gulf countries and Lebanon and Israel exchanged strikes.
The number of U.S. service members killed in the first three days of the war grew as officials said the remains of two more troops had been recovered.
President Trump’s embrace of military action in Iran was spurred by an Israeli leader determined to end diplomatic negotiations. Few of the president’s advisers voiced opposition.
In a brief interview, he said the country’s hardened military should simply surrender their weapons to the Iranian public.
The grim toll signaled that Iran was more prepared for war than the Trump administration anticipated, U.S. military officials said.
U.S. Central Command did not say where the troops were killed but added that five others had been seriously wounded and that several had shrapnel injuries.
President Trump has become increasingly willing to assert American power overseas, a decade after propelling himself to the highest office by promising to focus on “America first.”
The president made unsupported and exaggerated claims in a speech announcing the attack on Iran.
The notification stood in contrast to past military actions President Trump has undertaken unilaterally without consulting with Congress, drawing bipartisan anger.