General Dynamics Corp., the country's fourth-largest defense contractor, agreed yesterday to buy the defense businesses of telecommunications giant GTE Corp. for $1.05 billion in cash.

The move continues General Dynamics' recent buying spree, coming one month after the Falls Church company agreed to buy corporate-jet maker Gulfstream Aerospace Corp. for $5.3 billion in stock. In February, General Dynamics made an unsuccessful $2 billion bid for Newport News Shipbuilding Inc.

The GTE units had been for sale for some time; the phone company is seeking to shed unwanted businesses in preparation for its $80 billion merger with Bell Atlantic Corp. General Dynamics is buying three of four government- and defense-related GTE businesses, passing over a unit that does mostly commercial telecommunications work.

"This transaction is again solidly accretive to earnings and cash flow," said General Dynamics Chairman Nicholas D. Chabraja. "This is a transaction for which we anticipate significant synergies."

Wall Street analysts expect General Dynamics to earn $3.27 a share in 1999. Chabraja said the GTE purchase would add about 6 cents a share to earnings. The purchase is subject to regulatory approval and, barring any objections, should be completed within 60 days, he said.

"It's not surprising, and it's attractive," Cowen & Co. analyst Heidi Wood said of the deal. "I think it puts GD exactly where they want to be going."

General Dynamics shares, which have gained about 55 percent in the past 12 months, closed at $66.75, up 12 1/2 cents, in New York Stock Exchange trading.

With the latest two acquisitions, General Dynamics would solidify its position as the primary defense company below the tier of the Big Three -- Lockheed Martin Corp., Boeing Co. and Raytheon Co. The Gulfstream and GTE businesses would bring about $4 billion in annual revenue to the company, boosting annual sales to about $9.5 billion.

GTE's three units do about $1.2 billion in annual business, have a backlog of orders worth about $900 million and employ about 6,200 workers, mostly in Massachusetts and California. Much of the work the GTE companies perform is either for the military or intelligence agencies and is considered "black box," or classified in nature. It includes such things as providing cryptographic encoding of sensitive communications and secure computer and telephone networks for military personnel in the field.

The GTE businesses will join General Dynamics' information systems and technology group, which was formed last year after the company acquired Ceridian Corp.'s Computing Devices International as well as units of Lucent Technologies Inc. The group provides telecommunications and computer products and services to military customers.

CAPTION: NICHOLAS D. CHABRAJA