General Verissimo Correia Seabre has declared himself president of Guinea-Bissau after seizing power in a coup.
There are soldiers on the streets of the capital, Bissau, which is reported to be quiet and no shots have been fired.
What is Guinea-Bissau like?
Once hailed as a potential model for Third World development, Guinea-Bissau is now one of the poorest countries in the world.
Health conditions and rates of infant mortality, life expectancy and literacy are poor even by West African standards.
Much of its population of about 1.5 million people exists on less than 50 cents a day.
Added to this, the country experienced a bitter civil war in the late 1990s in which thousands were killed, wounded and displaced.
What caused the coup?
The immediate spark for the coup is thought to have been the repeated postponement of elections, originally scheduled to take place more than six months ago.
In a television interview, Guinea Bissau's new military leader, General Seabre, accused President Kumba Yalla of preparing to rig the elections.
Nonetheless, he said he had nothing against the president personally.
What happens now?
The general said President Yalla was free to remain in Guinea Bissau or to leave the country as he wished.
For the moment at least, though, the army says the president has been detained.
The general says he will remain leader until elections are organised in the West African state.
Soldiers say they are setting up a transitional government to include "all national political orientations".
Why is this important?
There are serious humanitarian concerns over the state of the country, as well as concerns about the knock-on effects of the instability for the surrounding region.
The economy is in tatters and public officials have not been paid for months.
The secretary general of the United Nations warned earlier this year that it was on a downward course and the Organisation of West African States expressed concern over human rights.
Guinea-Bissau has never really recovered from an uprising and war in the late 1990s, that left several thousand people dead and many more displaced.