WASHINGTON — The Obama administration on Friday announced a strategy to start slashing emissions of methane, a powerful greenhouse gas released by landfills, cattle, and leaks from oil and natural gas production.

The methane strategy is the latest step in a series of White House actions aimed at addressing climate change without legislation from Congress. Individually, most of the steps will not be enough to drastically reduce the United States’ contribution to global warming. But the Obama administration hopes that collectively they will build political support for more substantive domestic actions while signaling to other countries that the United States is serious about tackling global warming.

In a 2009 United Nations climate change accord, President Obama pledged that by 2020 the United States would lower its greenhouse gas emissions 17 percent below 2005 levels. “This methane strategy is one component, one set of actions to get there,” Dan Utech, the president’s special assistant for energy and climate change, said on Friday in a phone call with reporters.

Environmental advocates have long urged the Obama administration to target methane emissions. Most of the planet-warming greenhouse gas pollution in the United States comes from carbon dioxide, which is produced by burning coal, oil and natural gas. Methane accounts for just 9 percent of the nation’s greenhouse gas pollution — but the gas is over 20 times more potent than carbon dioxide, so even small amounts of it can have a big impact on future global warming.