US energy envoy Amos Hochstein arrived in Beirut on Wednesday, a week after Lebanon began drilling for hydrocarbons off its coastline.
Mr Hochstein last year helped mediate a landmark maritime border deal between Lebanon and neighbouring Israel, two countries technically at war with each other.
That rare agreement between the two sides, signed in October, meant Lebanon has been able to begin its search for oil and gas in an area known as Block 9.
The US State Departement said Mr Hochstein would visit Lebanon on Wednesday and Thursday “to follow-up on the historic October 2022 Maritime Boundary Agreement”. He “will also discuss areas of mutual and regional concern”.
Mr Hochstein's visit comes amid heightened tensions in the south between Lebanese armed group Hezbollah and Israel. Leaders of both sides have threatened to send each other back to the stone age if war were to break out.
President Joe Biden's energy envoy was dispatched last month to Israel amid the tensions.
The most recent war of words has been related to Hezbollah setting up tents in an area claimed by Israel, but both sides have exchanged fire in a series of small, often brief, clashes in recent years.
Israel and Hezbollah last fought a major war in 2006. The latter is a deeply influential and powerful Iran-backed group, whose arsenal is thought to be larger than the Lebanese Army's.
The Shiite group was the only Lebanese civil war militia allowed to keep its weapons.
The border between Israel and Lebanon is patrolled by UN peacekeepers. The renewal of the latter's mandate is to be discussed at the UN Security Council on Wednesday.