ISTANBUL -- The United States will deploy a rocket launcher system in southeastern Turkey across the border from Syria, officials said Tuesday.

U.S. Maj. Gen. Peter Gersten, deputy commander for the fight against Islamic State of Iraq and Syria (ISIS) militants, said that the mobile, long-range rocket system will be the fourth one deployed around the region.

Speaking from Baghdad to reporters at the Pentagon, Gersten noted that one is in Jordan, another is in Iraq's Anbar province and another is being deployed to help in the fight to retake the northern Iraqi city of Mosul.

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He wouldn't say where exactly in Turkey the system would be placed, but it could likely be used as the campaign progresses to retake ISIS de facto capital Raqqa in northern Syria.

"I will tell you that is a recent development that we have been working on, and we are looking at how it's going to be installed, and we're working very closely with our strong partners in Turkey to find out exactly how it's going to operate," he said.

In an interview with the Haberturk newspaper published on Tuesday, Turkish Foreign Minister Mevlut Cavusoglu said U.S. HIMARS missiles would arrive in May as part of a joint effort to combat ISIS.

Turkey regularly shells ISIS targets in northern Syria in response to cross-border rockets, which have hit the Turkish town of Kilis. Turkish shells have a range of approximately 25 miles whereas HIMARS missiles can reach targets 55 miles away. HIMARS stands for High Mobility Artillery Rocket System.

"In order to clear the area of Daesh, we have to give the moderate opposition both aerial and ground support," Cavusoglu said, using an alternate acronym for ISIS.

Clearing the Manbij area would pave the way for the creation of a "safe zone," he added.

Turkey has long advocated for the creation of a buffer zone in Syria, but failed to get its allies on board.

The nation is part of the U.S.-led coalition against ISIS and hosts 2.7 million Syrian refugees.

Evoking history and appealing for solidarity, President Barack Obama on Monday cast his decision to send 250 more troops to Syria as a bid to keep up "momentum" in the campaign to dislodge ISIS. He pressed European allies to match the U.S. with new contributions of their own.

Mr. Obama's announcement of the American troops, which capped a six-day tour to the Middle East and Europe, reflected a steady deepening of U.S. military engagement, despite the president's professed reluctance to dive further into another Middle East conflict. As Mr. Obama gave notice of the move, he said he wanted the U.S. to share the increasing burden.

"These terrorists are doing everything in their power to strike our cities and kill our citizens, so we need to do everything in our power to stop them," he said.

In December, President Obama admitted publicly for the first time that a small contingent of 50 or so elite U.S. commandos has begun working inside Syria to "tighten the squeeze" on ISIS.

CBS News correspondent Charlie D'Agata met one of the groups American military personnel are working with inside northern Syria -- the Syrian Democratic Force. It is a newly-formed group made up largely of Kurdish and Arab fighters.

A local commander told D'Agata he had met with U.S. forces on the ground in Syria who are helping to coordinate local militias, and providing equipment, intelligence and training. The commander said in addition to helping call in accurate airstrikes, the deployment symbolically shows that the U.S. is committed to the fight.

In neighboring Iraq, the Obama administration has also been incrementally increasing the American military presence in the fight against ISIS.

Last week, Defense Secretary Ash Carter said the U.S. will send 200 more troops and a number of Apache helicopters to Iraq to assist in the fight to retake Mosul, Iraq's second-largest city that is currently under ISIS control.

The decision reflect weeks of discussions with commanders and Iraqi leaders, and a decision by President Barack Obama to increase the authorized troop level in Iraq by 217 - or from 3,870 to 4,087.

Most of the additional troops would probably be Army special forces, who have been used to advise and assist the Iraqis. The remainder would include some trainers, security forces for the advisers, and more maintenance teams for the Apaches.