From mobilizing its allies in the Middle East to blocking shipping in a strategic waterway or even launching a cyber attack far beyond its borders, Iran has no shortage of options to avenge the killing of top commander Qasem Soleimani by its arch foe the United States.

Tehran's clerical leadership promised "severe vengeance... in the right place and time," but is nonetheless expected to carefully weigh the dangers of retaliation to a regime that has been in place since the ousting of the pro-American shah in 1979.

The unprecedented American raid that killed top Iranian commander Qasem Soleimani in Baghdad opens a period of uncertainty for the U.S. and their allies in the region.

It also raises questions over what happened, and what happens next.

The year 2019 saw an explosion of demonstrations across the world as people demanded an overhaul of entrenched political systems and action on climate change.

As chief of Algeria's military for a record 15 years, General Ahmed Gaid Salah became the country's de facto leader after longtime president Abdelaziz Bouteflika resigned in April.

His death from a heart attack at age 79, announced by state television on Monday, threatened to deepen Algeria's political crisis at the end of a turbulent year.

Turkey's parliament approved a security and military cooperation deal with Libya's U.N.-recognized unity government based in Tripoli on Saturday.

The Myanmar military launched a ferocious crackdown against its Rohingya Muslim population in 2017, driving around 740,000 into neighbouring Bangladesh.

Key dates in the history of Algeria ahead of its contentious December 12 presidential election.

Monday's summit aiming to end the conflict in eastern Ukraine will see Russia's Vladimir Putin face off with Ukraine's Volodymyr Zelensky for the first time.

The year 2019 saw an explosion of demonstrations across the world as people demanded an overhaul of entrenched political systems and action on climate change.

Iran has been gripped by protests since November 15, which broke out hours after the government raised fuel pump prices by at least 50 percent in the sanctions-hit country.

Here is a recap of the eruption of violence that followed.