The United States Air Force has increased the number of F-16 multi task Fighting Falcons to 18 from 12, two generals, quoted by Military.com said Tuesday at the Air Force Association's Air, Space and Cyber Conference.

In addition air refueling tankers are in Afghanistan for the first time in about five years, they said.

The Air Force now has 18 multi-role F-16 fighters in country, Lt. Gen. Jeffrey L. Harrigian, commander of US Air Forces Central Command, told reporters at the conference.

"We just plussed up our number of fighters. We had 12 F-16s; we now have 18," said Harrigian, who oversees missions at the Combined Air Operations Center at Al Udeid Air Base, Qatar.

According to Military.com, Harrigian said: "Our close-air support role continues and, as you look at the strategy coming forward, we're actually right now working with [Commander of US forces in Afghanistan] Gen. John Nicholson's staff on how to best synchronize his advice-and-assist strategy going forward to optimize the placement of the air assets."

Harrigian said there has been a large focus in the north and eastern part of Afghanistan in provinces such as Kunar and Kunduz.

"But there's a recognition that we're going to have to distribute our force, and that's going to require a lot of airpower support."

The emphasis will be on supporting ground forces as they position throughout the country. And Harrigian plans to "optimize" drones, such as MQ-9 Reapers, operating in the area, reported Military.com.

The US Defense Secretary Jim Mattis said Monday the United States will send in more than 3,000 additional troops to Afghanistan.

Mattis told reporters at the Pentagon he expected to sign an order sending the troops soon, but offered few details.

"The president has been very clear that we are not going to broadcast to the enemy how many [troops] are going [and] where exactly they are going," he said.