The Pentagon says Washington's new arms reduction treaty with Moscow will not impede US plans to develop missile systems, Press TV reported.
Patrick O'Reilly, who is the chief of the Pentagon's Missile Defense Agency, made the remarks at a Senate committee on Wednesday in an attempt to win support for the new treaty.
The new Strategic Arms Reduction Treaty (START) needs at least 67 votes to be ratified.
The Pentagon is working hard to convince the Republican lawmakers that the bill does not interfere with the country's new plan on missile systems.
"There are no limitations in the treaty that affect our plans for developing missile defense," said Patrick O'Reilly, Reuters reported,
The Republicans, however, have pointed to a clause in the new treaty which prohibits the conversion of long-range missile launchers into defense missile launchers.
Responding to the argument, O'Reilly said, "The options that are prohibited would be ones that we would not choose."
He added that such launcher conversions would no longer be necessary because officials have found it is cheaper to build new launchers than to convert old ones.
The new START that was signed by US President Barack Obama and Russian President Dmitry Medvedev last April requires Washington and Moscow to reduce their stockpile of nuclear arms.
The two countries together own 95 percent of the world's nuclear weapons.