WASHINGTON — The United States is rushing 1,000 antitank rockets to the Iraqi military to help combat the massive suicide vehicle bombs that Islamic State militants used in capturing the provincial capital of Ramadi, a first step as the Obama administration weighs a range of difficult options to help its beleaguered ally.

The deployment of the weapons, expected to arrive in early June after Prime Minister Haider al-Abadi of Iraq asked for them during a visit to Washington last month, comes as the defeated Iraqi security forces regroup outside the city. A senior State Department official said Wednesday that Iraqis were “licking their wounds a bit” as they worked with American advisers to begin planning a counterattack.

Obama administration officials have called the fall of Ramadi a huge setback, but they have sought to quell critics in the region and on Capitol Hill by portraying the defeat as a temporary blow that will not change the overall strategy for fighting the Islamic State or lessen the administration’s support of Mr. Abadi’s government.

Still, a day after Mr. Obama gathered his national security team to discuss the latest developments in Iraq and how to retake Ramadi, officials across the government expressed dismay at the rapid collapse of the Iraqi security forces in Ramadi and the tough decisions ahead. The Islamic State is at the same time making substantial gains across the border in Syria.