WASHINGTON — An expedited shipment of 2,000 lightweight shoulder-fired weapons intended to help the Iraqi army stop the Islamic State group's increasingly effective use of car bombs should arrive in Iraq as soon as next week, the Pentagon said Thursday.

The shipment is among a variety of weaponry and equipment the U.S. agreed to send to Iraq on an expedited basis after Iraqi Prime Minister Haider al-Abadi visited Washington in April to plead for more help in fighting the extremists.

Col. Steve Warren, a Pentagon spokesman, said the shipment of shoulder-fired AT-4 weapons was not in response to the fall of Ramadi over the weekend, although the militants' effective use of enormous car bombs there put a spotlight on Iraqi army deficiencies and prompted the White House to consider ways of strengthening U.S. support for Iraq.

A senior State Department official on Wednesday said the IS offensive in Ramadi over the weekend included about 30 suicide vehicle bombs, including 10 with a great deal of explosive power. Some of the vehicles used in the attacks were armored trucks that Iraqi defenders could not stop.

The AT-4 is relatively lightweight and is designed to penetrate armor, making the weapon useful in stopping what the military calls vehicle-borne improvised explosive devices, or car bombs, before they approach their intended target.

In an update to the overall cost of U.S. military involvement in Iraq and Syria, Warren said that as of April 9 the U.S. had spent $2.1 billion since it began bombing in Iraq in August. The Syria bombing campaign began the following month.