The European Union is set to unveil a fresh package of sanctions against Russia as western leaders staged a show of support for the beleaguered Ukrainian government.

Russia’s foreign minister has warned that Ukraine’s Nato ambitions are threatening to derail peace talks in eastern Ukraine.

Ukraine called yesterday for full membership in Nato, its strongest plea yet for Western military help, after accusing Russia of sending in armoured columns that have driven back its forces on behalf of pro-Moscow rebels.

Some of the trucks in a Russian aid convoy which entered Ukraine in a move denounced by Kiev as an invasion are reported to be returning to Russia.

The head of NATO says it has observed an "alarming" build-up of Russian ground and air forces near the Ukrainian border.

The White House has accused Russia of stepping up its destabilising activity in Ukraine in an “extremely dangerous and provocative” way.

Ukraine said its artillery destroyed part of a Russian armoured column that entered its territory on Thursday night and said its forces came under shellfire from Russia yesterday in what appeared to be a major military escalation between the ex-Soviet states.

Russian military vehicles crossed into Ukraine during the night, according to Nato and Ukraine, and the Ukrainian president said most of them were quickly destroyed by his troops.

Sustained shelling in the main rebel stronghold in eastern Ukraine struck residential buildings and a hospital, killing at least four people and wounding 10 others, officials said, as government forces pressed forward in their campaign to rout the separatists.

Russia has resumed a military build-up near Ukraine, Nato secretary general Anders Fogh Rasmussen says.

The United States is preparing to boost its military presence in Europe and at a cost of up to $1bn (€734m) President Barack Obama has said.

President Vladimir Putin flew in to Crimea yesterday for the first time since it was annexed by Moscow, proclaiming as he marked the Soviet victory in the Second World War that incorporating the former Ukrainian territory had made Russia stronger.

Top diplomats have agreed to take immediate steps toward calming tensions in Ukraine, Russia’s foreign minister says.

NATO is strengthening its military footprint along its eastern border in response to Russia’s aggression in Ukraine, the head of the alliance said.

Ukraine’s prime minister has told leaders in the east of the country that he is committed to allowing regions to have more powers.

Nato’s foreign ministers have ordered an end to civilian and military co-operation with Russia and told their generals and admirals to quickly devise ways to better protect alliance members that feel threatened by Moscow.

NATO secretary general Anders Fogh Rasmussen has confirmed Norway’s former premier Jens Stoltenberg will succeed him as new chief of the military alliance in October.

Almost 100 years ago, many of our grandparents and great grandparents went to war, often never to return.

US and Western diplomats yesterday failed to bring Russian and Ukrainian foreign ministers together for face-to-face talks on the confrontation in Crimea.

The head of Nato says it is responding to Russia’s military intervention in Ukraine by suspending most of the military alliance’s meetings with Russia and "intensify our partnership with Ukraine".

“This is a declaration of war... We are on the brink of disaster,” Ukraine prime minister Arseny Yatsenyuk warned, as Russian troops surrounded at least two military bases in Crimea and the country’s Naval commander defected to Moscow.

The United Nations chief has said his organisation's report into the use of chemical weapons in Syria is "indisputable".

The British Prime Minister David Cameron said there is no chance of reaching an international consensus on Syria.

David Cameron has firmly rejected pressure to go back to the British Parliament in a fresh attempt to seek MPs’ approval for involvement in military action in Syria, following the Prime Minister’s dramatic defeat last Thursday.

President Barack Obama has decided to authorise lethal aid to Syrian rebels but US officials are still grappling with what type and how much weaponry to send the opposition forces and how to ensure it stays out of the hands of extremists battling for control of Syria.

What an amazing week last week was for Irish neutrality.

Nato’s Secretary General tonight paid tribute to the brave, dedicated and selfless Irish men and women who have taken part in its missions.

Nato told Syrian President Bashar al-Assad yesterday that any use of chemical weapons in his fight against encroaching rebel forces would be met by an immediate international response.

Syria’s civil war is closing in on president Bashar Assad’s seat of power in Damascus with clashes between government forces and rebels flaring around the city today, raising fears the capital will become the next major battlefield in the 20-month-old conflict.

A mortar attack has killed 29 pupils and a teacher in a Damascus school, according to state media.

Turkey has called for Nato Patriot surface-to-air missiles to bolster its defences along its border with Syria.

Nato has declared it is ready to defend Turkey amid artillery exchanges along its tense south-eastern border with Syria.

Turkey has warned it will respond to any further military action by Syria following the shooting down of one of its jets.

Nato has invited Pakistan’s president to the upcoming Chicago summit on Afghanistan, the strongest sign yet that Islamabad is ready to reopen its western border to US and Nato military supplies heading to the war in the neighbouring country.

An assassin yesterday shot dead a former high-ranking Taliban official working on reconciling Afghanistan’s insurgency with the government — a fresh blow to peace efforts on the day Kabul announced it was gradually taking the lead from the US-led coalition for providing security in much of the country.

The Nato chief today pledged the alliance will hand over responsibility for securing Afghanistan to the country's domestic forces by the end of 2014 as scheduled.

Nato’s top official has joined the US and France in calling for Afghan forces to take the lead in all combat operations by mid-2013, while continuing to help in fighting the Taliban.

Nato’s triumphant, seven-month air campaign against Libya has ended, setting the country on the path to a democratic transition less than two weeks after the capture and killing of ousted dictator Muammar Gaddafi.

LIBYA’S interim rulers yesterday elected academic Abdel Rahim al-Kib to head a transitional government as NATO was set to end an air campaign that played a major role in ousting Muammar Gaddafi.

Nato says it will end its air campaign over Libya next Monday, following the UN Security Council decision to lift the no-fly zone and end military action to protect civilians.

Nato unexpectedly postponed a definite decision to end its bombing campaign in Libya as consultations continued with the United Nations and the country’s interim government over how and when to wind down the operation.

NATO plans to end its seven-month air and sea mission in Libya on October 31, but will issue a formal decision next week after consulting the United Nations and Libya’s interim authorities, Nato chief Anders Fogh Rasmussen said yesterday.

Nato Secretary-General Anders Fogh Rasmussen tonight announced the alliance is to wind down its operations in Libya ahead of a withdrawal at the end of this month.

Nato’s top commander says he will recommend the end of the alliance’s Libya mission.