WASHINGTON — President Barack Obama plans to use a speech in Berlin on Wednesday to outline plans for further reductions in the U.S. nuclear arsenal if Russia agrees to pare back its weapons at the same time, administration officials said Tuesday.

Resuming a drive toward disarmament that he had largely shunted aside over the past two years, Obama will propose trimming the number of strategic warheads that each of the two big nuclear powers still maintains by as much as a third, taking them below the 1,550 permitted in the treaty he signed with Russia in his first term, a senior administration official said. A scenario that leaves each country with just more than 1,000 weapons.

Obama also will declare that he will work with NATO allies to develop proposals for major cuts in tactical nuclear weapons, which are not covered by the existing treaty. Russia, which has more tactical nuclear weapons deployed than the United States and Europe do, has resisted such cuts.

Obama also will announce that he will host a final nuclear security summit meeting in the United States just before he leaves office.

The president faces enormous obstacles to any further reductions. Russian President Vladimir V. Putin has demanded further concessions on missile defense before entertaining deeper nuclear cuts, and Senate Republicans have made clear they would resist any treaty that went beyond the New START pact ratified in 2010.