WASHINGTON (AP) -- The U.S. Navy's top officer says that Iran's naval forces have refrained from provocative moves against U.S. ships in the Persian Gulf in recent months, while continuing a regular pattern of naval exercises.

Adm. Jonathan W. Greenert told a Pentagon news conference that the Iranian navy has been "professional and courteous" and has abided by the international norms that govern naval activity in international waters.

Previous provocations generally came from the naval arm of the Iranian Revolutionary Guard Corps, which is separate from the regular Iranian navy. Greenert said the Revolutionary Guard's navy in the past has tended to operate too close to U.S. ships, but that this has not happened in the last couple of months.

The U.S. Navy 5th Fleet has a constant presence in the Gulf region.