The United States will propose on Wednesday implementing a United Nations arms embargo on South Sudan and further targeted sanctions from Sept. 1 unless President Salva Kiir signs a peace deal to end a 20-month conflict, a diplomat said.

A draft resolution was due to be circulated to the 15 members of the U.N. Security Council shortly, the diplomat said, speaking on condition of anonymity, adding that the plan was to vote on the text before the end of the month.

The arms embargo and further targeted sanctions would come into force on Sept. 1 unless U.N. Secretary-General Ban Ki-moon notified the council that both sides to the conflict had signed a peace deal brokered by regional leaders, the diplomat said.

Kiir asked for another 15 days of discussions, shrugging off pressure to meet a Monday deadline. Kiir also told U.S. Secretary of State John Kerry on Wednesday he intends to sign a peace deal.

South Sudan plunged into civil war in December 2013 when a political crisis sparked fighting between forces loyal to Kiir and rebels allied with his former deputy Riek Machar. The conflict has reopened ethnic fault lines that pit Kiir’s Dinka against Machar’s ethnic Nuer forces.

Machar accepted the peace deal on Monday.

The Security Council blacklisted six rival generals in South Sudan in July, the first people to be subjected to a global asset freeze and travel ban.

U.N. peacekeeping chief Herve Ladsous pushed the U.N. Security Council last month to impose an arms embargo on South Sudan, where U.N. troops are sheltering more than 100,000 civilians at several sites around the country.

Diplomats said the council could not agree on imposing an arms embargo when it set up the sanctions regime in March, with the United States, Russia and China opposed to it, while European and other council members were in favour.

China’s U.N. Ambassador Liu Jieyi said on Tuesday that he hoped a peace deal could be reached in South Sudan. “I think we should work harder to move the two sides together,” he said.

(Reporting by Michelle Nichols, editing by G Crosse)