Iran reportedly test fired a ballistic missile that travelled 1,000 kilometres on Thursday, as tension between Iran and the US and UK increase in the Gulf.
A Pentagon official told CNN the Shahab-3 missile did not pose a threat to shipping or US bases.
The test occurred after the UK's new Prime Minister, Boris Johnson, ordered the Royal Navy to accompany all British-flagged ships through the Strait of Hormuz.
Iran seized British-flagged tanker Stena Impero in retaliation for the UK seizing Iranian tanker Grace 1 off the coast of Gibraltar.
On Thursday, US Secretary of State Mike Pompeo said he was willing to go to Iran for talks if asked.
Iran's ballistic missile programme was one of the reasons US President Donald Trump gave for withdrawing the US from a nuclear deal signed between Tehran and world powers, and reimposing sanctions.
