(ABC News)

ABC News' David Kerley and Stephanie Liu report:

The United States is intensifying its strikes in Yemen and increasing its presence there as it pursues al Qaeda.

Two suspected U.S. drone strikes killed 11 suspected al Qaeda militants in southern Yemen Saturday, according to military officials in the country. The news comes on the heels of an escalation in drone activity.

Just two days earlier, two airstrikes in southern Yemen killed seven, including two top al Qaeda leaders. And merely a week ago a drone strike killed Fahd Mohammed Ahmed al-Quso, the Yemeni al Qaeda operative responsible for 2000's USS Cole bombing.

The strike Saturday near the border of Marib and Shabwa provinces is the third to have been carried out this month. The United States conducted six airstrikes in March and at least six more in April against al Qaeda in the Arabian Peninsula (AQAP), the militant Islamist organization primarily active in Yemen and Saudi Arabia. In fact, there have been nearly as many drone strikes already this year as there were all of last year.

Last week, the Pentagon announced that they had resumed sending troops to Yemen to train the country's counterterrorism forces. The move comes after a suspension of training following the political upheaval that ousted former Yemeni President Ali Abdullah Saleh.

While the United States still has a long way to go, it's making progress, according to former CIA and FBI official Philip Mudd.

"We've gone into the network of the organization," Mudd said, referring to al Qaeda groups. "The same strategy it seems to me is now being applied in Yemen. That is, look at the entire organization, not just a few leaders, and decimate it from the inside."

While the escalation in drone strikes is not aimed at any one terrorist, officials would undoubtedly like to get Ibrahim al-Asiri, a Saudi bomb maker adept at breaching aviation security. The Yemen-based Asiri has drawn Defense Department scrutiny for his ability to fashion bombs using hard-to-detect chemicals and hiding them in equipment and clothing.

U.S. officials believe Asiri is the man behind the underwear bomb used by a Nigerian man to try and detonate an aircraft over the United States in 2009. He's believed to be plotting another attack, putting his ingenious chemical bombs in cameras, hard drives and, surprisingly to some, surgically implanting them in pets and even people.

According to Mudd, such an attack like this is not only a possibility, it's quite likely.

"You get to a point if especially there aren't parts you can identify by X-ray, especially metal parts, it could be very difficult to find these kinds of people," he said.

During Thursday's Pentagon briefing, Secretary of Defense Leon Panetta said U.S. military and intelligence units will continue zeroing in on the southern Arabian region, with the help of Yemeni forces on the ground.

"We will continue to take all of the steps necessary to try to go after those who would threaten our country and threaten our - the safety of American people," Panetta said. "The Yemenis have actually been very cooperative in the operations that we have conducted there.  And we will continue to work with them to go after the enemies that threaten the United States."