WASHINGTON - The United States remains steadfast in its call for Syrian President Bashar Assad to step down, even as the Arab nation has agreed to allow in Arab monitors, the State Department said on Tuesday.

"No, our view has not changed that Assad needs to step down, that he is not the man to lead his country into the future," department spokeswoman Victoria Nuland said at a regular news briefing.

"This Arab League proposal, we believe, offers the best opportunity to end the violence immediately so that Syria can move on to the next stage, which is a period that we hope will lead to real dialogue about a democratic future, which, frankly, we don't think Assad is capable of being part of," she said.

Syria signed on Monday a peace plan brokered by the Arab League aiming to end the violence in the Arab nation, under which the regional bloc will send monitors to conduct a field study of the situation in Syria.

Syria was plunged into turmoil in mid-March when anti- government protests broke out, and clashes between protesters and security forces have resulted in more than 5,000 deaths, as the United Nations figure shows.

The Arab League and Turkey have joined the US and European countries in imposing targeted sanctions on Syria, in the hope of pressing it to end violence on protesters.

The Syrian government blamed "armed groups and foreign conspiracy" for the turmoil in the country.

"We are concerned that there are delaying tactics here. We've always been concerned about that, which is why we want to see these monitors start deploying by the end of the week and the deployment be complete by the middle of January as the Arab League has hoped will happen," Nuland said.

She said that the US and the European Union have been in close touch with the Arab League and both "want to test the Syrian government's willingness to implement all aspects of the Arab League's proposal and particularly its commitment to unfettered access for human rights monitors into Syria now."

She also called for the Syrian government to implement three other aspects of the Arab League plan -- stopping all acts of violence, withdrawing armed elements from populated areas and releasing all political prisoners.