"We signed a new MoU on the expansion of our presence at al-Udeid. It hosts thousands of US military personnel and the CENTCOM forward headquarters. This place is key to American security", Pompeo said after signing a bilateral deal to expand the military base.
Al-Udeid is already the largest US military base in the Middle East.
The military base in Qatar is home to the US Air Force Central Command (AFCENT). It houses as many as 11,000 personnel and is critical for the projection of US air power in the region.
The senior official has also urged the Gulf States to end a rift in relations.
"We are all more powerful when we are working together and disputes are limited. When we have a common challenge, disputes between countries with shared objectives are never helpful", he said at a press conference in Qatar.
Qatari Foreign Minister Mohammed bin Abdulrahman Al-Thani, for his part, said that he had discussed the situation in Syria and the fight against terrorism, among a number of other issues of mutual interest, with Pompeo.
"We have held an extended dialogue during the seven meetings of the conference of dialogue between Qatar and the United States and discussed all issues of mutual interest, in particular, the crisis between the Gulf countries, the Middle East [peace] process, talks on Afghanistan, the situation in Syria, and efforts aimed at combating terrorism", Al-Thani said at a press conference after his meeting with Pompeo.
Pompeo arrived in Doha earlier in the day from Abu Dhabi, where he had travelled as part of his Middle East tour. The secretary's next stop will be in Saudi Arabia.