The United States and Russia have agreed to a new nuclear arms treaty that will be signed April 8 in Prague, Czech Republic, President Obama announced Friday after speaking with his Russian counterpart.

The treaty substantially cuts the nuclear weapons that the United States and Russia will deploy and will significantly reduce missiles and launchers, Obama said. It follows a 1991 treaty that expired in December and about which the United States and Russia have been negotiating.

“In many ways, nuclear weapons represent both the darkest days of the Cold War, and the most troubling threats of our time,” Obama said. “Today, we have taken another step forward in leaving behind the legacy of the 20th century while building a more secure future for our children.”

Obama also said the treaty would show that the United States and Russia, the world’s major nuclear powers, intended to lead on the issue.

“By upholding our own commitments under the nuclear nonproliferation treaty, we strengthen our global efforts to stop the spread of these weapons, and to ensure that other nations meet their own responsibilities,” the president said.

Obama said the treaty was part of his effort to improve relations with Russia.

“Since I took office, I have been committed to a “reset” of our relations with Russia,” Obama said.

“When the United States and Russia can cooperate effectively, it advances the mutual interests of our two nations, and the security and prosperity of the wider world. We have worked together on Afghanistan. We have coordinated our economic efforts through the G-20. We are working together to pressure Iran to meet its international obligations. And today, we have reached agreement on one of my administration’s top priorities - a pivotal new arms control agreement,” he said.

Secretary of State Hillary Rodham Clinton, who also attended Obama’s briefing, said the agreement shows “deep and substantive cooperation on a matter of vital importance” with Russia and that “patient principled diplomacy can advance our national interests.”

Defense Secretary Robert Gates, who addressed reporters along with Clinton, said the reductions would not hurt the United States.

According to the White House, the agreement would require both Russia and the United States to reduce their long-range warheads to 1,500. This is 74% lower that the START number in 1991 and 30% lower than the limit of the 2002 Moscow Treaty.

Obama and Russian President Dmitry Medvedev discussed the treaty in a telephone conversation Friday morning. It was their 14th direct meeting or phone call on the issue.

Prague was chosen for the treaty signing to commemorate the anniversary of Obama’s April 5, 2009, speech in the Czech capital where he offered his vision for reducing global nuclear arsenals.

“I am pleased that almost one year to the day after my last trip to Prague, the Czech Republic -- a close friend and ally of the United States -- has agreed to host President Medvedev and me on April 8th, as we sign this historic treaty,” Obama said.

The treaty represents part of his administration plans to deal with nuclear weapons, Obama said.

“The following week, I look forward to hosting leaders from over forty nations here in Washington, as we convene a summit to address how we can secure vulnerable nuclear materials so that they never fall into the hands of terrorists. And later this spring, the world will come together in New York to discuss how we can build on this progress, and continue to strengthen the global non-proliferation regime. “

The treaty will require Senate approval. Earlier this week, Obama met with Sens. John Kerry (D-Mass.) and Richard Lugar (R-Indiana) to discuss passage.