Congresswoman IIhan Omar has condemned an Al-Shabaab attack on US Naval Base in Lamu, calling for concerted effort to "counter" terrorism.
The Somalia-based militants claimed responsibility for the deadly attack which solely targeted Kenyan and American troops.
Camp Simba plays host to American soldiers not more than 100, Associated Press said. Kenyan troops are also deployed in the station, it added.
US Africa Command (AFRICOM), which is responsible for the military in Africa, confirmed that one US Serviceman and two American contractors were killed.
Omar, who serves as Minnesota 5th District Representative, termed the attack "chilling", besides mourning those who died.
"The Al-Shabaab attack against U.S. forces in Kenya is the latest in a chilling escalation of terror attacks in Africa. My heart breaks for all who lost their lives," she tweeted.
Omar, a Somalia refugee, added: "We must remain committed to securing peace in the region and stand against terrorism."
She is the most senior US leader to issue a statement following the attack, the first ever attempt on a US military base on Kenyan soil.
US Africa Command leader General Stephen Townsend insisted that America will continue working closely with allies to defeat Al-Shabaab.
The US, he added, will ensure the group is completely neutralised or wiped out for the sake of security in East Africa.