Ukraine on Thursday raised hopes of a ceasefire with pro-Moscow rebels during a NATO summit where Britain and the United States urged the international community to stand up to Russia and counter the threat from Islamic State. President Petro Poroshenko briefed leaders, including US President Barack Obama and German Chancellor Angela Merkel, and said he expected a deal to be signed on Friday "for the gradual introduction of the Ukrainian peace plan". The separatist administrations in the regions of Donetsk and Lugansk in Ukraine also said they were ready to issue a ceasefire order if the Kremlin-backed peace plan is signed, but the reaction in Newport in Wales was cautious. German Foreign Minister Frank-Walter Steinmeier said on the sidelines of the meetings that "small confidence or optimism is growing that we are maybe on the way towards the de-escalation of the conflict". President Francois Hollande called for a "real ceasefire" that would lead to a broader political agreement and said France would only deliver warships worth 1.2 billion euros to Russia if these conditions were in place. As the summit billed by NATO as one of its most important since the Cold War continued, AFP reporters heard explosions on the outskirts of the flashpoint city of Mariupol where Ukrainian officials said they had repelled a rebel tank attack. Russian Foreign Minister Sergei Lavrov also lashed out after British Prime Minister David Cameron and US President Barack Obama argued in an article in the Times newspaper that Russia had "ripped up the rulebook" over Ukraine. Lavrov denied Russian military involvement and accused the United States of undermining peace efforts by supporting "a pro-war party" in Kiev. He said Washington was "drunk on anti-Russian rhetoric" after repeated accusations from the West that Russia is training and supplying rebels and sending its soldiers into Ukraine. The summit is expected to create trust funds for Ukraine's military, set up new high-readiness units and position troops and equipment in former Soviet bloc NATO members unnerved by Russia's involvement in the conflict in Ukraine. - Britain, US to 'confront' radicals - Ukraine tops the agenda at the two-day talks, but the 28 NATO leaders must also tackle the menace of Islamist extremists in Iraq and Syria and a problematic withdrawal from Afghanistan. Cameron and Obama said they would not be "cowed" following the beheading of two US journalists by Islamic State jihadists and promised to "confront" the radicals. NATO chief Anders Fogh Rasmussen also said the alliance would "seriously" examine any request from Iraq for help in its campaign against the Islamic State, while Cameron said Britain was actively considering arming the Kurds. "To the east, Russia is attacking Ukraine, To the southeast we see the rise of a terrorist organisation, the so-called Islamic State," Rasmussen said as he arrived for the summit, adding: "We will take important steps to counter these threats." sceptical about the proposal - Sanctions on Russia - In a clear effort to seize the initiative ahead of the summit, Russian President Vladimir Putin unveiled a plan on Wednesday which he said would produce a ceasefire on Friday -- the same day the European Union is expected to announce additional economic sanctions against Moscow. French President Hollande said the sanctions would be approved on Friday "if there has been no progress". "Everything will depend on the next few hours," he told reporters at the summit. But a British government source said the sanctions were sure to go ahead. NATO has accused Russia of sending hundreds of troops and tanks into Ukraine in what Rasmussen has warned is the most serious security threat to Europe since the Cold War. NATO sees Russia's March annexation of Crimea from Ukraine as a violation of the 1997 NATO-Russia Founding Act which fixed Europe's post-Cold War borders and prohibited the use of force to change them. There is speculation that the landmark treaty could now be revoked, although Rasmussen has insisted that the planned NATO commitments in Eastern Europe do not breach its terms -- as Russian actions have done. - Withdrawal from Afghanistan - NATO meanwhile faces another quandary in Afghanistan, where the alliance is due to end its combat operation this year, but finds it has no government to hand over to as presidential elections have failed to produce a winner. Rasmussen warned that time was running out for a solution, raising doubts about NATO's planned post-2014 training mission after it formally concludes its longest-ever war this year. "Time is short," he said.