Diplomacy with Iran must be backed by military power, U.S. Defense Secretary Chuck Hagel has said. Hagel, speaking in Bahrain, said Washington was committed to maintaining a strong force in the Gulf region, according to BBC News.
Iran recently agreed to curb some nuclear activities for six months in return for sanctions relief. Analysts say Washington's Gulf Arab partners are worried the U.S. will lose focus on the Middle East as it boosts its presence in Asia.
Hagel told the Manama Dialogue - a regional security forum - the U.S. has more than 35,000 military personnel in the region and would not reduce that number.
"We know diplomacy cannot operate in a vacuum," Hagel said. "Our success will continue to hinge on America's military power, and the credibility of our assurances to our allies and partners in the Middle East."
"Iran has been a profoundly destabilising influence and a nuclear-armed Iran would pose an unacceptable threat to regional and global stability," he added.
Under the interim deal agreed with six world powers in Geneva, Tehran will receive some $7bn in sanctions relief while talks continue to find a more permanent agreement.
Although the accord was generally welcomed, Israel said it was a "historic mistake" and some U.S. senators have said it is too soft on Iran. Hagel said the agreement "bought time for meaningful negotiation, not for deception".
He said U.S. diplomacy would ultimately be backed up by military commitments and co-operation with regional partners.