Kerry was to depart Washington late yesterday after accompanying President Barack Obama to Cuba and speaking by phone from Havana with the Belgian foreign minister to offer condolences for the victims of the attacks and any assistance Brussels might need.
The attacks were claimed by the Islamic State group and have highlighted the threat the group poses outside of its territory in Iraq and Syria.
In talks with Russian President Vladimir Putin and Foreign Minister Sergey Lavrov tomorrow, Kerry is to discuss the fragile truce in Syria that is hoped will spark UN-brokered peace talks amid disagreements over how to verify and respond to alleged violations, the State Department said.
Russia on Monday warned the United States that it will start responding unilaterally to cease-fire violations in Syria if the US refuses to coordinate rules of engagement against violators. The State Department, however, insisted that Moscow and Washington are working constructively to monitor the truce.
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The department also warned Russia against taking unilateral action in response to alleged violations. The Russian military has accused the US of dragging its feet on responding to Moscow's proposals on rules for joint monitoring of the Syria cease-fire and response to violations. It said that further delays are leading to civilian casualties.
Savchenko was convicted of complicity to murder in the 2014 deaths of two Russian journalists in eastern Ukraine, opening a door to a possible prisoner swap between the two countries.
The US has repeatedly called for Savchenko, who is also a member of parliament, to be released and did so again yesterday.