U.S. Assistant Secretary of State for African Affairs Johnnie Carson met briefly with Somali officials last weekend, the first such visit by a U.S. official in nearly 20 years.
Somalia is preparing to end a formal transitional period in August as interim leaders make slow administrative gains against militant group al-Shabaab, which seeks an Islamist state in the country.
Carson was quoted by the BBC as saying Washington would hit those suspected of standing in the way of Somali peace with stiff penalties.
"The kind of action we must take against spoilers range from visa sanctions to travel sanctions to asset freezes," he said. "There is a level of vulnerability for all of those who might be spoilers."
The U.S. State Department last week authorized a reward of up to $7 million for information leading to the location of al-Shabaab founder Ahmed Abdi aw-Mohamed. Lesser rewards were offered for other key al-Shabaab figures.
Somalia needs to adopt a new Parliament and a new constitution before the formal transition period ends Aug. 20.