Donald Trump has said North Korean leader Kim Jong Un "will regret it fast" if he continues his threats to US territories and allies.

The United States will respond by September 1 to Russia's attempt to force a major reduction in American diplomatic staff, Rex Tillerson has said.

Russian foreign minister Sergey Lavrov is threatening "counter actions" against the United States over a pair of Russian diplomatic compounds seized by the United States last year.

US president Donald Trump has described his lengthy head-to-head encounter with Russian president Vladimir Putin as a "tremendous meeting".

Russia is trying to verify reports that its military has killed the leader of the Islamic State group in an air strike targeting a meeting of militant leaders.

Donald Trump's national security adviser has insisted the US president's revelations to Russian officials about the terrorist threat from Islamic State were "wholly appropriate" and amounted to a routine sharing of information.

Donald Trump will meet Vladimir Putin's senior diplomat at the White House on Wednesday in a signal that US relations with Russia have improved.

Russia, Iran and Turkey are ready to act as guarantors in a peace deal between the Syrian government and the opposition, Russian foreign minister Sergey Lavrov said.

Russian foreign minister Sergey Lavrov has warned Syrian rebels in Aleppo that they will be wiped out unless they agree to stop fighting and quit the besieged city.

US Secretary of State John Kerry is threatening to cut off all contact with Moscow over Syria, unless Russian and Syrian government attacks on Aleppo end.

The United States, Russia and more than a dozen other countries have declared that Syria's ceasefire is not dead despite increasing violence on the ground.

World and regional powers have agreed to try and turn a fragile truce in Syria into a comprehensive ceasefire.

Russia has accused the Ukrainian government of dragging its feet on implementing last year’s cease-fire agreement.

US secretary of state John Kerry said yesterday that a “provisional agreement” has been reached on a ceasefire that could begin in the next few days in Syria’s five-year civil war.

US secretary of state John Kerry, in a visit to Moscow yesterday, sought to make progress in narrowing differences with Russian leader Vladimir Putin over how to end the conflict in Syria.

Russia's deputy defence minister has accused Turkish president Recep Tayyip Erdogan and his family of personally profiting from oil trade with militants from the so-called 'Islamic State' group.

In a move raising the potential threat of a Russia-NATO conflict, Russia says it will deploy long-range air defence missiles to its base in Syria and destroy any target that may threaten its warplanes after the downing of its military jet by Turkey.

Russia has called on Washington to restart direct military-to-military co-operation to avert “unintended incidents” near Syria, at a time when US officials say Moscow is building up forces to protect president Bashar al-Assad’s government.

Ceasefire under threat as Independence Day imminent

US secretary of state John Kerry yesterday expressed “gave concern” to his Russian counterpart about a sharp rise in separatist attacks in eastern Ukraine and urged an immediate ceasefire, the State Department said.

Russia has said it will be at least six months before it can deliver a missile system to Iran, but the Kremlin confirmed a barter deal to supply Russian goods in exchange for Iranian oil was already being implemented.

The foreign ministers of Iran and six world powers met in a final push for a preliminary nuclear accord before their deadline today as Tehran showed signs of backing away from previous compromise offers.

Russian foreign minister Sergey Lavrov said the killing of opposition leader Boris Nemtsov was a “heinous crime which will be fully investigated”.

Ukraine’s military has said it will start pulling back its heavy weapons from the front line with Russian-backed separatists as required under a ceasefire agreement.

Ukraine’s president has pushed for a quick ceasefire in his country’s troubled east, insisting that the conflict must be resolved and not “frozen,” and pressed Kiev’s case to be supplied with defensive weapons.

At least seven people are reported to have been killed when a city bus was hit by an artillery shell in a separatist stronghold in east Ukraine.

Diplomats from Russia and Ukraine agreed on a dividing line from where both sides should pull back their heavy weapons.

Separatist forces in eastern Ukraine have deployed large quantities of arms and manpower to an emerging flashpoint, undermining hopes for a new peace initiative taking shape.

Government troops and Russian-backed separatists have largely suspended hostilities in east Ukraine in a fresh attempt to revive a largely ignored ceasefire deal.

Russia’s foreign minister has urged those holding a new round of talks on easing Ukraine’s crisis to push for a ceasefire between Ukrainian government troops and pro-Russian separatists.

The news that the Ukrainian military is battling rebel armoured vehicles that crossed from Russia and headed towards Mariupol does not auger well for today’s meeting between Russian and Ukrainian presidents in Minsk. It suggests that Russia is determined to copper-fasten its authority in the region. The Ukraine’s response, and that of its allies, will shape events, but it seems difficult to predict a peaceful outcome.

Ukraine has claimed that rebels in the east of the country fired rockets and mortars on civilians trying to flee from the region’s intense fighting.

Moscow is ready for a direct dialogue with Ukraine’s new president and does not need any Western mediation, Russia’s foreign minister has said.

The United States and other nations in the Group of Seven have agreed to “move swiftly” – as early as Monday – to impose additional economic sanctions on Russia for its actions in Ukraine.

Russia’s foreign minister has promised a firm response if its citizens or interests come under attack in Ukraine – a vow that came after Ukraine announced a renewal of its “anti-terror” campaign against those occupying buildings in its troubled east.

Ukraine is launching a “large-scale anti-terrorist operation” to resist attacks of armed pro-Russian forces, Ukraine’s President Oleksandr Turchynov said in a televised address.

Russia has set out demands for a diplomatic resolution to the crisis in Ukraine, saying the former Soviet republic should be unified in a federation allowing wide autonomy to its various regions.

Russia has set out demands for a diplomatic resolution to the crisis in Ukraine, saying the former Soviet republic should be unified in a federation allowing wide autonomy to its various regions.

Russia's Foreign Minister says his country has no intention of sending its armed forces into Ukraine.

Vladimir Putin has called US president Barack Obama to discuss a diplomatic solution to the Ukrainian crisis.

Russia has demanded more autonomy for Ukraine’s regions as the pressured nation ordered its troops out of Crimea.

Washington and the international community won’t recognise the outcome of tomorrow’s referendum in Crimea on seceding from Ukraine, US secretary of State John Kerry said after six hours of talks with Russia’s foreign minister.