Washington (AP) - Thirteen defense executives are complaining that the threat of automatic, across-the-board cuts to military spending is creating uncertainty that's already affected their industry.

Seven senators released copies of the executives' letters on Monday. The six Republicans and Joe Lieberman, D-Conn., are trying to ratchet up the political pressure to force Congress and President Barack Obama to produce a deficit-cutting plan to avert the cuts before they kick in Jan. 2.

However, no action is expected until after the election.

The executives from such companies as Lockheed Martin Corp., Raytheon Co., Boeing Co., and Northrop Grumman Corp., said the looming cuts had not affected current contracts. But they warned of an impact on the industry and its workforce if the indiscriminate reductions go into effect.

Jay Johnson, the chairman and CEO of General Dynamics, said the Defense Department acquisition process is already beginning to slow in anticipation of sequestration reductions. The uncertainty surrounding the ultimate nature of sequestration is "already affecting our investment and hiring activities and this will accelerate as the months pass," Johnson wrote.

General Dynamics is the parent company to Electric Boat in Groton.

"While precise outcomes are impossible to predict at this juncture, we can be assured that the disruption and confusion that will result and its impact on the national defense would be profound," he wrote. "The toll this uncertainty would have on the skilled people of General Dynamics and our suppliers should not be underestimated."