Sheik Sabah Al Ahmed Al Sabah was sworn in as the new emir of Kuwait on Sunday, ending an unprecedented leadership crisis in the oil-rich U.S. ally that saw the legislature vote to oust the former leader.

Earlier Sunday, parliament voted unanimously to name Sheik Sabah the new leader — the first time in Kuwait's history that the legislature played a role in choosing the emir, a matter that had been the business of the ruling family for hundreds of years.

The ceremonies ended a leadership struggle and a dispute within the ruling Al Sabah family that had ballooned into a crisis after Sheik Jaber Al Ahmed Al Sabah died Jan. 15, leaving an ailing prince as his successor.

The new emir, who had been prime minister and half brother of the deceased emir, wore a white Arab robe and headdress as he took the office of office.

"We will adhere to the interests of the public and avoid sectarian and tribal considerations in every respect so that Kuwait will be the lone winner," he said before an audience that included 700 dignitaries and ambassadors.

The new leader also touched on Kuwait's tumultuous history since Iraq invaded its tiny neighbor in 1990. Thirteen years later, U.S.-led troops used Kuwaiti territory to launch the invasion that toppled Saddam Hussein.

"Our world is facing changes and developments on which we cannot turn our backs," he said. "The regional arena is witnessing aspects of tension and instability which put all of us at the core of real confrontation."

Before the vote, lawmakers called the new leader the "emir of reform" and the "hope of Kuwait" for a better future.

Legislator Mohammed al-Saqr called on the new emir to appoint an heir-apparent quickly to prevent a repeat of the succession crisis.

"What is needed it the appointment of a crown prince before appointing a prime minister," he told the house chamber.

Until 2003, positions of crown prince and prime minister were held by one man. That changed when Sheik Saad Al Abdullah Al Sabah, the former crown prince, fell ill and became unable to act as prime minister two years ago.

He briefly ascended to the throne after Sheik Jaber's death, but was only seen in public in a wheelchair and did not speak to the people. It became increasingly clear that his failing health would not allow him to carry out his responsibilities as head of state.

On Tuesday, the parliament removed him from power after hearing medical testimony that he was incapacitated. The legislature transferred his powers to the Cabinet, which met hours later and named Sheik Sabah the next emir. That vote was sanctioned by the 1964 succession law and the 1962 constitution.

Moments after voting to remove him, the parliament received an abdication letter from Sheik Saad. The ruling family had announced it had worked out the succession dispute, but it was too late to get the letter of resignation to the legislature before the unprecedented vote to remove the emir.