Pentagon leaders expect to soon give President Obama a plan for specific U.S. nuclear cuts to bring the arsenal in line with arms control caps.
A number of alternatives have been under contemplation for reducing deployed bomber aircraft and land- and submarine-based ballistic missiles to meet a limit of 700 delivery systems and 1,550 warheads under the New START agreement, which entered into force in February 2011.
"We've looked at this problem very, very hard over the last year," Adm. James Winnefeld, the vice chairman of the Joint Chiefs of Staff, said in response to a question from Representative Jim Langevin (D-R.I) at a Thursday hearing.
He said defense leaders are "close" to finalizing a recommendation.
"It's a vexing challenge to look at all of the factors involved and the relative advantages of decreasing [intercontinental ballistic missile] silos and decreasing [submarine-launched ballistic missile] tubes on submarines," Winnefeld told members of the House Armed Services Committee.
Internal Pentagon discussions surrounding the matter had been "spirited," the No. 2 military officer added.
At issue is how the Pentagon will alter its mix of delivery vehicles for nuclear weapons -- ground-launched Minuteman 3 missiles, submarine-launched Trident D-5 missiles, and bombers -- to meet limits of the New START agreement with Russia. Beyond the 700-system cap, 100 delivery platforms are allowed in reserve.
Congress already has waded into the debate. Lawmakers from states hosting the nation's 450 Minuteman missiles are attempting to block the Pentagon from starting even initial studies into the possibility of closing a portion of their underground launch silos.
Winnefeld on Thursday decried the Pentagon's inability to proceed with assessing launch-silo requirements, arguing that insights from such analyses are badly needed for future decisions.
In questioning Winnefeld, Langevin indirectly criticized congressional opponents to possible reductions.
"I, for one, would feel much better knowing that decisions made regarding what constitutes a safe, secure and effective deterrent triad is informed by the best judgment of our uniformed leaders about how to balance a deterrent, rather than shaping the nation's nuclear force based on parochial interests," the lawmaker said.