WASHINGTON (Reuters) – Parts of a proposal by Egypt for a truce in Libya are “helpful,” but a United Nations-led bid to broker peace in the North African country is the best way forward, the State Department’s top Middle East diplomat said on Thursday.

The oil-producing state descended into chaos after the NATO-backed overthrow of leader Muammar Gaddafi in 2011. Since 2014, Libya has been split, with the internationally recognized government controlling the capital, Tripoli, and the northwest, while military leader Khalifa Haftar in Benghazi rules the east.

Haftar – who launched an offensive a year ago to grab Tripoli – is supported by the United Arab Emirates, Egypt and Russia, while the government is backed by Turkey.

On Saturday, Egypt called for a ceasefire starting on Monday, as part of an initiative that also proposed an elected leadership council. Turkey dismissed the proposal, saying the plan aimed to save Haftar after the collapse of his offensive.

While Washington has said it opposes Haftar’s offensive, it has not thrown its support behind the government. David Schenker, U.S. assistant secretary for Near Eastern Affairs, appeared to largely knock down Cairo’s proposal on Thursday.

“We think there are parts of the initiative that are helpful. … That said, we think that the U.N.-led process and the Berlin process are really … the most productive frameworks … to make progress on a ceasefire,” Schenker said.

Libya’s warring parties have started to engage in a new round of ceasefire talks, the U.N. political mission in Libya said on Wednesday.

Ghassan Salame, who headed the U.N. mission and was charged with trying to mediate peace, quit on March 2 because of stress, days after his latest effort at peacemaking failed.

U.N. chief Antonio Guterres has suggested that former Ghana foreign minister and current U.N. envoy to the African Union, Hanna Tetteh, head the U.N. Libya mission. The United States has said it could support her appointment, diplomats said.

Schenker confirmed that but added that running the U.N. political mission and brokering peace were “quite a big task for one person, so we’re … talking with our counterparts about the best way forward.”

Diplomats said that before agreeing to Tetteh’s appointment, Washington wants Guterres to name a special envoy to focus on mediating peace in Libya and has proposed former Danish Prime Minister Helle Thorning-Schmidt.

The U.N. Security Council traditionally greenlights such appointments, but some of the 15 members are not in favor of the U.S. proposal to split the role, diplomats said.