Ukrainian President Petro Poroshenko used his speech at the U.N. General Assembly on Tuesday to rail against Russian aggression, urging the world not to believe "conciliatory" statements from his counterpart Vladimir Putin.

The Russian leader called Monday for a broad U.N.-backed coalition to fight the Islamic State group as he seeks to muscle his way back onto the world stage after months of isolation over Ukraine.

U.S. Secretary of State John Kerry suggested Tuesday that Russia and Iran may persuade Syrian strongman Bashar Assad to stop indiscriminately dropping barrel bombs on his own people.

Moscow and Washington disagree sharply about Assad's longer term role in efforts to end the Syrian war, but have begun cautiously to discuss efforts to defeat his Islamic State jihadist foes.

Moscow on Tuesday slammed the holding of a U.S.-led counter-terrorism summit at the United Nations, calling it disrespectful.

On Tuesday, President Barack Obama sat down with more than 100 leaders at the U.N. to push ahead with a U.S.-led campaign against the Islamic State group.

Lithuanian President Dalia Grybauskaite on Tuesday slammed her Russian counterpart Vladimir Putin for a speech he delivered at the United Nations General Assembly that she said was reminiscent of Soviet-era totalitarianism.

The outspoken leader of the formerly Soviet-ruled, EU state said Putin's criticism of the West suggested he "was still living in the 20th century".

Nearly 30,000 foreigners have traveled to Iraq and Syria to join jihadists since 2011 and the United States is failing to stop Americans from heading overseas to join them, a report warned Tuesday.

The document describes a national security infrastructure that is ill-equipped to deal with the myriad ways foreign jihadists contact and recruit Americans.

U.S. President Barack Obama said Tuesday that defeating the Islamic State group in Syria will only be possible if Bashar Assad leaves power, a day after a clash with Russia over the Syrian president's fate.

"In Syria (...) defeating ISIL requires, I believe, a new leader," Obama told a counter-terrorism summit of some 100 leaders, held on the sidelines of the U.N. General Assembly.

Germany toughened rules Tuesday for asylum seekers from the Balkans as Europe struggled to cope with a record surge in migrants, with those crossing the Mediterranean exceeding the half a million mark.

Berlin added Albania, Kosovo and Montenegro to a list of so-called safe origin countries, which will result in swifter deportations for asylum seekers from those conflict-free states, in a bid to free up resources to deal with claims from citizens of war-torn countries like Syria.

Moscow said on Tuesday that Russia and the United States intended to build upon a key meeting between Vladimir Putin and Barack Obama and look for ways to fight the Islamic State group.

The Russian president stole the show at the U.N. General Assembly on Monday, calling for a broad U.N.-backed coalition to fight Islamic State jihadists.

Russian President Vladimir Putin has stolen the spotlight at the United Nations with a swaggering push on the Syria crisis as he tried to shake off Western isolation over Ukraine.

In his first speech to the UN General Assembly in a decade, Putin on Monday called for a broad UN-backed coalition to fight Islamic State (IS) jihadists before sitting down to talks he called "constructive, business-like and surprisingly open" with his U.S. rival Barack Obama.

Russian President Vladimir Putin and his U.S. counterpart Barack Obama met Monday on the crisis in Syria but failed to resolve their dispute over the future role of Bashar Assad.

In dueling speeches before the U.N. General Assembly, Obama branded the Syrian leader a child-killing tyrant while Putin said the world should support Assad against the Islamic State group.