The South Korean air force will start aerial refueling drills with the United States on a regular basis this year, a military official said.

"The F-15K and KF-16, our two main air force fighters, are capable of refueling in mid air but have never completed air-to-air refueling in our skies," an unnamed military official told South Korea's Yonhap news agency. "We will conduct the refueling exercise with a U.S. tanker every six months."

The official said a U.S. Air Force Boeing KC-135 Stratotanker, stationed at Kadena Air Force Base in Okinawa, Japan, will be dispatched for the first drill in August or September.

The official gave no firm date for the first refueling exercise.

South Korea has been interested in aerial refueling for many years because of the advantages it would give its air force during prolonged confrontations, notably with North Korea.

Fighter aircraft can take off with less fuel and heavier payloads than normal with the aim of refueling in flight. Also, refueling allows the aircraft to increase its strike distance.

But a more poignant strategic issue during times of crisis is the aircraft can continue to fly awaiting orders to strike. This cuts out the time for an aircraft to takeoff and reach its target, possibly saving valuable minutes.

However, when South Korea's Defense Department suggests procurement of KC-135 Stratotankers or similar aircraft, financial alarm bells ring within government circles in Seoul. They are expensive, despite their age.

Users of the KC-135, apart from the United States, are France, Singapore and Turkey. The last KC-135 was delivered to the U.S. Air Force in 1965 and around 190 usable aircraft remain at the disposal of the military.

The refueling deal with the United States comes as South Korea's Department of Defense is seeking a 6.6 percent budget increase for next year. The ministry has requested an annual budget of $31.3 billion, of which just more than $4 billion is to strengthen South Korea's military presence in the islands off its west coast with the latest weapons and base facilities.

No aerial refueling aircraft has been on the Defense Department's shopping list. But in March, South Korea said it aims to purchase a number of drones and stealth fighters starting around 2015 as part of the delayed acquisition F-X program.

"We will acquire high-altitude unmanned reconnaissance planes to boost our surveillance capability against the enemy," South Korean Defense Minister Kim Kwan-jin said. "Last year we endured North Korea's grave provocations. ... Now is the time to act boldly and wisely to make our military strong enough in the face of pending security threats."

A contract for buying Northrop Grumman RQ-4 Global Hawks -- unmanned surveillance vehicles -- also could be signed, a South Korean military source told Yonhap earlier this month.