The company left its 2022 financial guidance unchanged. Demand for its Himars and Javelin missile systems and F-35 combat jets increased in the wake of Ukraine-driven tensions. However, executives at defense companies have said it could take several years for the interest to turn much of this into orders and sales.

Lockheed Martin added another $5 billion to its backlog of orders during the September quarter, raising the total to $140 billion. The company said only a fraction of this relates to Ukraine.

Lockheed Martin announced plans to double its share buyback program for 2022 and repurchase $14 billion of its own stock over the next three years.

The Pentagon has announced more than $17 billion in military assistance to Ukraine. About $3 billion is under contract with defense companies such as Lockheed, the department has said. The U.S. and its allies are taking steps to coordinate purchases and address supply-chain kinks that have limited increased production of in-demand weapons.

Russia’s invasion of Ukraine has triggered pledges by European governments to boost military spending, and the U.S. Congress is on track to increase the domestic defense budget above the request from the White House. 

Jay Malave, Lockheed’s chief financial officer, said it would be 2024 before elevated international demand showed up as higher sales. He forecast a low single-digit rise in sales in 2024, with around $10 billion in potential “upside” over the next several years from new international deals.

The company had previously expected sales to rise around 2% next year, and supply-chain problems will also hit margins, he said.

Production of the F-35 and F-16 jets and some missile systems has been hit by a combination of parts and labor shortages. “We saw no meaningful improvements in the third quarter,” said Mr. Malave, citing metrics such as on-time delivery.

Lockheed Martin maintained its full-year sales target of $65.25 billion for 2022 and per-share earnings of $21.55, with the outlook for cash flow and operating profit also unchanged.

Profit rose to $1.78 billion in the quarter to Sept. 25 from $614 million a year earlier following a pension charge, with sales up 3% at $16.6 billion. Per-share earnings increased to $6.71 from $2.21, above the $6.57 consensus among analysts polled by FactSet.

Write to Doug Cameron at Doug.Cameron@wsj.com