Iran announced Wednesday that it successfully tested another "Sajil" missile, a surface-to-surface missile with a range that makes it capable of reaching parts of Europe, CNN reported.
A similar test was carried out in November.
U.S. Defense Secretary Robert Gates said he understood Wednesday's test of the missile - with an approximate range of 1,200 miles - was successful.
State media reported that the missile - a Sajil-2 - was launched Wednesday morning from the northern Iranian city of Semnan and reached its target. The report did not say where it landed.
A White House official said the test is noteworthy.
"I think it is a significant technical development," said Gary Samore, special assistant to the president on nonproliferation, in a Washington speech Wednesday. "... Of course, this is just a test, and obviously there is much work to be done before it can be built and deployed. But I see it as a significant step forward in terms of Iran's capacity to deliver weapons.
"And I think it actually helps us in terms of making a case to countries like Russia, which were skeptical in the past whether Iran actually poses a threat. This is a very clear demonstration that Iran is moving in the direction of longer-range missiles."