Senegalese troops have succeeded in entering The Gambia to ensure Adama Barrow assumes power as the country’s new president.
He has been recognised internationally, but Yahya Jammeh has refused to quit.
West African leaders have threatened to remove Mr Jammeh by force. The UN has backed their support for Mr Barrow.
Senegalese army spokesman Col Abdou Ndiaye was quoted by news agencies as saying the country’s troops entered The Gambia on Thursday afternoon.
Nigeria said earlier in the day that its “armed reconnaissance air force are over Gambia”, AFP reports.
“They have the capacity to strike,” Nigerian Air Force spokesman Ayodele Famuyiwa told the news agency.