WASHINGTON (AP) -- As U.S. forces gear up for airstrikes in Syria, the first demonstration of President Barack Obama's more aggressive military campaign against the Islamic State group is likely to unfold first in Iraq as early as next week, officials say.
In Syria, U.S. planes and drones will be gathering intelligence on targets and air defense threats in preparation for airstrikes there. At the same time, a wider range of targets - perhaps including Islamic State leaders - are expected to come under attack in Iraq.
U.S. warplanes have launched 158 strikes in Iraq over the past five weeks while emphasizing a relatively narrow set of targets. The focus has been Obama's initial goal of defending U.S. personnel, protecting critical infrastructure such as major dams and enabling humanitarian relief operations.
New strikes Friday destroyed two Islamic State armed vehicles in an effort to support Iraqi troops near the Mosul Dam and in defense of Irbil, the military's U.S. Central Command said.
More U.S. troops, along with additional intelligence-gathering aircraft, are expected to arrive in northern Iraq next week. That will enable an expanded surveillance effort over Syria by a range of aircraft, including Predator and Reaper drones as well as Navy EA-18G electronic warfare planes that are capable of jamming air defense radars and striking ground targets.
Without citing a specific timeline, the Pentagon's press secretary, Navy Rear Adm. John Kirby, said the air campaign in Iraq, which began Aug. 8, will enter a new, more aggressive phase designed to exploit the Islamic State group's vulnerabilities, which include a lack of effective defenses against U.S. warplanes.
"In coming days we're going to be more aggressive and shift a focus from what has been to date primarily defensive in nature to more offensive in nature," he said. He suggested that this will include strikes at Islamic State leaders in Iraq.
"When you are going after a network like this, one of the things that you also want to go after is their ability to command and control and to lead their forces," Kirby said.
The aim is not to destroy the Islamic State forces in Iraq by air power alone, but rather to erode their capabilities and limit their freedom of movement so that Iraqi ground forces can regain control of territory they lost in recent months.
One of the risks being weighed by Obama and his military commanders as they prepare to extend the airstrikes into Syria is that country's air defenses, which have been described as formidable. They are less prominent, however, in the more desolate eastern stretches of Syria where U.S. warplanes are likely to fly.
Kirby declined to discuss the air defense threat in detail.
"Generally speaking, the eastern part of the country is more desolate, more remote, less critical infrastructure there than in the western part of the country, so, generally speaking, one would assume that most of their air defense systems are based around the west and around major facilities and major cities," he said.
But, he said, air defense systems can be moved and thus must be monitored.
"As we plan and prepare for the possibility of conducting airstrikes across that border, we're obviously factoring in every possible contingency that we can," he said.
The Obama administration has sought to portray the president's strategy, as outlined in his speech Wednesday, as more than a military campaign. It says regional and international diplomacy are equally important. And it has been careful to distinguish this effort from the wars in Iraq and Afghanistan.
Pressed on whether the United States was engaging in a new war, White House press secretary Josh Earnest argued that it was the Islamic State group that was waging war on the world and that the U.S. was leading a coalition to ultimately destroy it.
"What you can conclude from this is the United States is at war with ISIL in the same way that we are at war with al-Qaida and its al-Qaida affiliates all around the globe," Earnest said, using an acronym for the Islamic State.
A key element of the Obama strategy is developing a viable opposition force inside Syria that can not only exploit gains created by U.S. airstrikes against the Islamic State but also advance the U.S. goal of ousting Syrian President Bashar Assad. A first step in that direction is a Pentagon plan for training and arming Syrian rebels - a project Saudi Arabia has agreed to host on its territory.
Kirby said the Pentagon foresees training more than 5,000 Syrian rebels in Saudi Arabia over the coming year. He said it would be "a number of months" before that effort would start, in part because prospective Syrian rebels must be vetted in advance to ensure their reliability as a U.S. partner in Syria.
Associated Press writers Jim Kuhnhenn and Lolita C. Baldor contributed to this report.