The Kremlin has announced that Vladimir Putin and Barack Obama have agreed to increase cooperation on counter-terrorism in the wake of the Boston Marathon bombings.
A manhunt ended in Watertown, Massachusetts last night, almost 24 hours after police first hit the trail of the two suspects, Dzhokhar Tsarnaev and his 26-year-old brother Tamerlan, immigrants of Chechen origin who lived in nearby Cambridge.
Police believe they planned and executed the bombing last on Monday, which killed three and injured over 100.
Dzhokhar, 19, is now in police custody, and his brother was killed in a shoot-out.
Chechnya is ruled by neighbouring Russia, and its largely Muslim population - who have lived for centuries in the mountainous North Caucasus - have resisted Russian rule for the past 200 years.
Today a Kremlin spokesperson said that during a phone call the two leaders, "underlined their interest in deepening the close cooperation of the Russian and US special services in the fight against international terrorism," but gave no details.
The White House said President Obama had thanked President Putin for Russia's cooperation after the bombing.
"President Putin expressed his condolences on behalf of the Russian people for the tragic loss of life in Boston," the White House said in a statement.
Putin has not commented on the identity of the two suspects, who moved to the United States more than a decade ago after briefly living in Russia's volatile southern region of Dagestan.
Kremlin spokesman Dmitry Peskov said on Friday Putin had repeatedly made clear that Russia condemned all acts of terror, regardless of who carried them out.
The Russian-installed leader of Chechnya, Ramzan Kadyrov, criticised police in Boston for killing an ethnic Chechen and blamed the violence on his upbringing in the United States.
And in his weekly address to the US people, President Obama said: "After a vicious attack on their city, Bostonians responded with resolve and determination. They did their part as citizens and partners in this investigation.
"Over the past week, close coordination among federal, state, and local officials - sharing information, moving swiftly to track down leads - has been critical to this effort.
"They all worked as they should, as a team. And we are extremely grateful for that.
"Why did young men who grew up and studied here, as part of our communities and our country, resort to such violence? How did they plan and carry out these attacks, and did they receive any help?
"The families of those killed so senselessly deserve answers. The wounded, some of whom now have to learn how to stand and walk and live again, deserve answers.
"We will determine what happened. We will investigate any associations that these terrorists may have had. And we'll continue to do whatever we have to do to keep our people safe."