President Barack Obama's administration is looking at possible cuts to the US nuclear arsenal that include a drastic option to reduce the number of warheads by up to 80 percent, a US official said Wednesday.

But no decision has been taken yet on how to reshape the nuclear force, officials said, as the White House prepares for more arms control negotiations with Russia and an international nuclear summit next month in Seoul.

The United States now has 1,790 deployed warheads and has to scale back the number to 1,550 by 2018 under an arms control agreement with Russia.

The policy review underway suggests a range of additional cuts that include reducing the arsenal to 1,000 to 1,100, another that proposes dropping to 700 to 800 or shrinking the force dramatically to 300 to 400 warheads, the US official, who spoke on condition of anonymity, told AFP.

"Three hundred (warheads) is the very low end of those options," the official said.

"No proposals have been made to the president. This thinking is in its early stages."

In keeping with longstanding US policy, any reduction in the arsenal likely would only be carried out as a result of arms negotiations with Russia.

Slashing the arsenal down to about 300 deployed warheads would represent a dramatic break with American strategy and downsize the atomic force to a level not seen since the 1950s.

Obama vowed to work for a world free of nuclear weapons in a speech in Prague in 2009 and has championed arms control as a hallmark of his presidency, a stance that helped him win the Nobel Peace Prize.

The details of the administration's nuclear review comes ahead of a nuclear security summit in South Korea in March. Obama launched the forum in 2010, touting the session as a way to bolster international safeguards and prevent nuclear terrorism.

Media reports about potential cuts to the nuclear force triggered a sharp response from Republican lawmakers in Congress on Wednesday while the US military's top officer, General Martin Dempsey, sought to play down the chances of a massive reduction.

When asked by Representative Mac Thornberry at a House hearing, Dempsey declined to confirm or deny that the administration was looking at options that included the 300-400 warhead range.

But he said keeping the arsenal at full strength was also a possibility.

Reports about possible reductions amounted to a simplified "Cliff Notes version" of the policy review, said the general, the chairman of the Joint Chiefs of Staff.

"It's the Cliff Notes version of what is a very comprehensive set of discussions internal to the military with the national security staff on what is our next negotiating strategy, notably with Russia," Dempsey told the House Armed Services Committee.

"The status quo by the way is always an option and one that is in play."

Dempsey sought to reassure the Republican lawmaker, saying: "At this point sir, I'd encourage you not to become too concerned with the media reports about what is a very comprehensive process."

But Thornberry said he remained alarmed and that such a reduction would prompt other countries to build up their arsenals.

Slashing the force by up to 80 percent "does nothing but encourage our enemies and discourage our friends," Thornberry said.