MANAMA, Bahrain — Iran is trying to build a nuclear bomb, posing a threat to its neighbors, and the United States is “very ready” to counter Iran should it make a move, the top U.S. military officer said Saturday.

Adm. Mike Mullen, chairman of the Joint Chiefs of Staff, sought to reassure Persian Gulf nations nervous that an increasingly militarized government in Iran might try to start a war.

“The United States takes very seriously our security commitments in the Gulf region,” Mullen said following a meeting with Bahrain’s king. Bahrain, directly across the Gulf from Iran, is home to a large U.S. Navy base that would be on the front lines of any war with Iran.

“We’re very ready,” Mullen said, an unusually direct acknowledgment that the United States has contingency plans to counter Iran should it make a move. “There are real threats to peace and stability here, and we’ve made no secrets of our concerns about Iran.”

Iran denies it is seeking a nuclear weapon, and denies U.S. claims that it sponsors terrorists. Iran has wary relations with many of its neighbors, who are trading partners with the oil giant but distrust the theocratic government.