AMMAN, Jordan — The deputy head of the Muslim Brotherhood in Jordan was sentenced on Sunday to 18 months in prison for criticizing the United Arab Emirates in a Facebook post.

The state security court, a special body that has jurisdiction over Jordan’s internal and external threats, found the Brotherhood leader, Zaki Bani Rushaid, guilty of “acts harmful to the country’s relations with a friendly nation.”

On his personal Facebook page, Mr. Bani Rushaid wrote on Nov. 17 that the Emirates, an important ally of Jordan and one of several countries in the region, including Egypt and Saudi Arabia, that have engaged in a campaign to wipe out the Brotherhood, plays the role of the “American cop in the region, supports coups and is a cancer in the body of the Arab world.”

The Muslim Brotherhood in Jordan condemned the verdict in a statement released on Sunday. The arrest of Mr. Bani Rushaid, under a recently strengthened antiterrorism law, was “politically motivated and demonstrates a deliberate escalation by the state against the Muslim Brotherhood in Jordan,” the statement said. “It is a blow to freedom of speech and the rights of citizens.”