US Defence Secretary Robert Gates will consider sending some 3,000 Marines to Afghanistan to thwart any spring offensive by Taliban militants, the Pentagon has said.
"This proposal is coming before the secretary this week," Pentagon press secretary Geoff Morrell said. "He will take it and consider it thoroughly before approving it."
Violence has surged in Afghanistan over the past two years, with the Taliban fighting a guerrilla war in the south and east and carrying out high-profile suicide and car bombings across the country.
For months, Mr Gates has pressed Nato allies to provide more troops for Afghanistan. But if the Pentagon chief backs the proposal, it will show Washington has concluded it will have to provide a large share of any extra combat forces.
Mr Gates ordered a boost in US forces early last year in response to the violence and the United States currently has some 27,000 troops in Afghanistan - a record high.
Around half the US troops serve in a 40,000-strong Nato-led security assistance force while the rest conduct missions ranging from counter-terrorism to training Afghan troops.
While Nato says it thwarted last year's attempted Taliban spring offensive, overall violence is up 27 per cent over a year ago and it has risen by 60 per cent in the southern province of Helmand, the US military said last month.