WASHINGTON, Feb 5 (Reuters) - India has agreed to buy six Lockheed Martin Corp (LMT.N: Quote, Profile, Research) C-130J military transport planes in a breakthrough deal with the United States worth about $1 billion, opening a door to closer strategic ties, U.S. officials said on Tuesday.

India and the U.S. signed an agreement on Jan. 31 for Lockheed to start delivering the four-engine Super Hercules turboprop aircraft in 2011, said Bruce Lemkin, who handles U.S. Air Force international affairs.

The deal marks a major shift in weapons-buying policy by India, which for decades has relied heavily on Russian arms and transport aircraft.

"It really provides the centerpiece of a growing relationship between our two air forces," Lemkin, a deputy undersecretary of the air force who had been working on the matter for almost two years, said in a telephone interview. Continued...