Former US secretary of state Hillary Clinton said Friday she would likely decide whether she will join the 2016 presidential race by the start of next year.
Clinton, who lost the Democratic presidential nomination to Barack Obama in 2008, is widely expected to make another run for the White House.
"I will be making a decision around probably after the first of the year about whether I am going to run again or not," the former first lady said in Mexico City at a forum hosted by the Telmex Foundation of Mexican billionaire Carlos Slim.
"It's a very serious undertaking, so obviously I'm thinking about it, but I have not made a decision yet," said Clinton, who has previously indicated that she would not make an announcement before the end of this year.
Speaking to 10,000 young Mexicans who have received Telmex Foundation scholarships, Clinton shared her life experiences but also briefly touched on world affairs, voicing concern about Russia's role in the Ukraine conflict.
"I do worry about President Putin's view that Russia should dominate its borders and intimidate people beyond its borders, using gas and oil as a weapon, even where we are seeing now with Ukraine, military force," she said.
"It is very important that Europe remain whole, stable and at peace and that Russia be persuaded or somehow convinced, even coerced, into looking toward the future, not the past," said Clinton, who served as the top US diplomat during Obama's first term between 2009-2013.
Before her appearance, Ukraine and pro-Moscow rebels signed a ceasefire agreement in Minsk, raising hopes for an end to the five-month war.
Obama, speaking at the end of a NATO summit in Wales, said US and European Union sanctions against Russia over the crisis would likely remain in place despite the ceasefire but could be lifted if the truce holds.
About 2,600 people have died in fighting in east Ukraine between government forces and pro-Russia rebels that Kiev maintains are armed by Moscow.