A YEAR AGO this month the Persian Gulf emirate of Bahrain took an unusual and seemingly important step toward ending a simmering conflict between the ruling al-Khalifa family and a mass opposition movement. King Hamad bin Isa al-Khalifa listened as an international jurist accused the regime of gross human rights abuses, including excessive police force, torture, coerced confessions and unfair trials. The king promised to implement 26 reform recommendations by the Bahrain Independent Commission of Inquiry.

That promise has gone unfulfilled. A forthcoming report by the Project on Middle East Democracy finds that only three of the 26 measures have been fully completed. The most important ones — on the release of political prisoners and relaxation of controls on free expression — have been ignored. The convictions of leading regime opponents, along with doctors who treated protestersfollowing demonstrations, have been reconfirmed. One of the country’s leading human rights activists, Nabeel Rajab, has been imprisoned.

On Oct. 30 the regime took the extreme step of banning public protests. On Wednesday, it revoked the citizenship of 31 people, including exiled opposition leaders and former members of parliament. In short, rather than reforming and seeking accommodation with the opposition, it is becoming more repressive. That is helping to radicalize the opposition: In a worrisome escalation, five bombs exploded around the capital of Manama on Monday, killing two people.

Bahrain is no Syria; the island state of 1.5 million has suffered only a fraction of the thousands of deaths caused by the regime of Bashar al-Assad. But like Syria, Bahrain is divided along sectarian lines: The regime is Sunni, while most of the population is Shiite. And its failing record matters particularly to the United States, because Bahrain is a close ally and host of the U.S. Navy’s 5th Fleet.

The Obama administration has spoken openly about what it perceives as conflicting interests in the country. Secretary of State Hillary Rodham Clinton once talked about the need to “walk and chew gum” in relations with the emirate, maintaining the security relationship while pressing for political change.

Yet, like the ruling family, the administration has failed to fulfill its promises. The State Department has monotonously issued statements expressing “concern” or declaring itself “troubled” as political prisoners it sought to free are instead resentenced and new measures of repression are taken. But the words are not accompanied by actions. After holding up one military sale under pressure from Congress last year, the administration released the equipment several months ago. It recently supported a Bahraini nominee for an advisory position at the U.N. Human Rights Council.

Such actions damage U.S. credibility across the Middle East, where many observers note that the United States is backing a Sunni rebellion in Syria while defending a Sunni autocracy in Bahrain — thus appearing to take sides in the region’s growing sectarian rivalry. Worse, the policy is laying the groundwork for the eventual loss of the alliance and the naval base: The Bahraini autocracy, like others in the Middle East, will not last. For the United States, democratic reform in the emirate is not a luxury but a vital interest. Walking without gum-chewing will lead to a bad stumble.