Chancellor Angela Merkel congratulated US President Barack Obama on the ratification of the Strategic Arms Reduction Treaty (START) and said she "hoped other steps in the direction of disarmament would follow," a statement said.
By ratifying the deal, the United States "sets the course for a decade of disarmament and affirms President Obama's vision for a world free of nuclear weapons," Foreign Minister Guido Westerwelle added.
"We are counting on Russia to now also ratify the treaty quickly," he said.
"A successful conclusion of 'New START' would be a quantum leap for the worldwide efforts at nuclear disarmament and a clear signal that both leading nuclear powers take seriously their disarmament obligations."
Westerwelle has consistently put nuclear arms reductions as a top priority for his term as foreign minister and urged leaders around the world to work towards a long-term goal of ridding the world of such weapons.
Disarmament and arms control were "pressing tasks" and Germany would use its place in the UN Security Council over the next two years to push "further concrete advances," Westerwelle said.
START would restrict each of the former Cold War foes to a maximum of 1,550 deployed warheads, a cut of about 30 percent from a limit set in 2002, and 800 launchers and bombers.
Russian Foreign Minister Sergei Lavrov also welcomed the US ratification but said Moscow needed time to study the US documents before doing the same as
there may have been amendments to a draft.