The United States welcomes the agreement signed between Ukrainian President Viktor Yanukovych and the opposition leaders.

"The United States welcomes the agreement signed today between Ukrainian President Yanukovych and opposition leaders. Now, the focus must be on concrete action to implement this agreement, which we will be monitoring closely," the Office of the Press Secretary of the White House said in a statement.

The United States calls for immediate implementation of the initial steps – an end to the violence, amnesty and security normalization, and passage of the constitutional package in the [Verkhovna] Rada – to provide space for the negotiations to begin on formation of a technocratic coalition government.

According to the statement, there must be accountability for those responsible for the violence and the casualties that have resulted since the crisis began.

"We remain prepared to impose additional sanctions as necessary," the statement says.