U.S. President Barack Obama said Wednesday that the United States and Russia are completing negotiations on a successor treaty for the Strategic Arms Reduction Treaty (START).

"The United States and Russia are completing negotiations on the farthest-reaching arms control treaty in nearly two decades," he told Congress in his first annual State of the Union speech.

Obama noted that the United States is reducing nuclear warhead stockpiles and launchers while ensuring adequate deterrent.

Calling nuclear weapons "perhaps the greatest danger to the American people," Obama said he has embraced the vision of a world without them.

Obama also said 44 nations will come together in April's Nuclear Security Summit, conveying a clear goal: securing all vulnerable nuclear materials around the world in four years, so that they never fall into the hands of terrorists.

Earlier in the day, Obama called his Russian counterpart Dmitry Medvedev. The two presidents agreed the negotiations on a successor treaty for the START are nearly complete, the White House said. Obama thanked Medvedev for his hard work and leadership on the negotiations, as the two sides have made steady progress in recent weeks.

The United States and Russia have been working on a successor to the START that expired on Dec. 5, 2009. However, differences over verification and control arrangements prevented the two sides from producing such a document last year.

The START, signed in 1991 between the Soviet Union and the United States, obliged both sides to reduce the number of their nuclear warheads to 6,000 and delivery vehicles to 1,600.

Medvedev and Obama agreed last July to slash each country's nuclear warheads to 1,500 and 1,675 and delivery vehicles to 500 and 1,000 respectively under a new START treaty.