The Gambia’s opposition says longtime ruler Yahya Jammeh could be considered a rebel leader if he takes up arms and doesn’t step down later this month, a warning issued after the president vowed any foreign troop presence would be tantamount to an act of war.

Halifa Sallah, the spokesman of the opposition coalition, said on Monday that Jammeh will be a private citizen as of January 19 and would have no constitutional mandate to be in command of the armed forces of The Gambia.

The president of ECOWAS – the Economic Community of West African States – has said West African leaders will send troops into the country if Jammeh refuses to step down after losing the December 1 election.

“Any president whose term of office expires who takes up arms against an incoming president whose term should begin according to law, would be regarded by the international community as a rebel leader,” Sallah said, reading a statement by the coalition.

Jammeh railed against the West African regional bloc ECOWAS that has urged him to step down. He claims numerous voting irregularities invalidate the December 1 ballot won by the opposition coalition’s Adama Barrow. Jammeh’s party is challenging the results in court.