The US government said yesterday it was "strongly encouraged" by the speech of Gerry Adams calling on the IRA to end violence.
But it stressed it would wait to see "concrete actions" by the IRA.
"We welcome the statement by Gerry Adams," a State Department spokesman said in Washington.
"We are strongly encouraged by his call for the Irish Republican Army to renounce violence and rely on purely political and democratic means."
He added: "We await concrete action by the IRA to support the policy advocated by Mr Adams. Respect for the rule of law is an essential element of the democratic society that Mr Adams has outlined. We strongly endorse this vision and once again call for all paramilitary activity and criminality to cease."
The spokesman said the US remains steadfast in its support for the peace process.
While the Sinn Féin leader was snubbed by President George Bush and Senator Edward Kennedy during his St Patrick's week visit to Washington, he had a meeting with the US envoy to Northern Ireland Mitchell Reiss and other Irish-American lawmakers.
Sources on Capitol Hill said Mr Adams assured them he was 90 per cent of the way to achieving the end of violence by the IRA.
Congressman James Walsh, chairman of the Friends of Ireland in Congress, said Sinn Féin negotiator Martin McGuinness called him on Wednesday to tell him that Mr Adams' speech was the "most important speech Gerry has made in 10 years".