Ukraine on alert after 'build-up of Russian troops'
Ukraine's president has put the country's armed forces onto combat alert amid renewed reports of a Russian troop build-up in the disputed region of Crimea.
The order came a day after President Vladimir Putin accused Ukraine of launching cross-border raids into the Russian-controlled peninsula that killed two servicemen.
"I ordered a high-level alert of all units in the region of the Autonomous Republic of Crimea and along the entire contact line in Donbass," Mr Poroshenko said after meeting with his national security council yesterday afternoon.
Earlier, Mr Putin chaired a meeting with Russian security chiefs to discuss "additional measures for ensuring security for citizens and essential infrastructure in Crimea," the Kremlin said in a statement.
Russia annexed Crimea before supporting a separatist insurgency in eastern Ukraine in 2014, sparking a war that has killed over 9,500 people. Crimea itself has previously been unaffected by the violence in eastern Ukraine.
Moscow and Kiev have accused one another of dangerous troop build-ups in recent weeks, raising fears of a return to the all-out warfare that tore Ukraine apart in 2014.
Russia's Federal Security Service said one of its officers and one soldier were killed in a series of fire-fights on Crimea's frontier with Ukraine between Saturday night and Monday morning.
Three Ukrainians captured during the skirmishes confessed to planning a series of explosions in the region's resorts in a bid to sow panic and destroy the Crimean tourism industry, security sources told Russian media.
Meanwhile, both government and Russian-backed separatists have reported a surge in violence in Ukraine's Donetsk and Luhansk regions, with nightly battles erupting along the line of contact despite a nominal ceasefire.
Mr Putin said the weekend attacks made French and German-brokered talks with Mr Poroshenko at the G20 summit in China next month pointless.
Cancellation of the meeting would raise serious concerns about the viability of a peace road map Mr Putin and Mr Poroshenko agreed in Minsk in February 2015.
Ukraine's border guard service said on Wednesday that Russia was massing modern equipment, including armed assault units, in Crimea and on Ukraine's eastern border. .
Earlier on Thursday the Ukrainian armed forces announced scheduled exercises in the south of the country.
"The events are developing according to a pretty negative scenario," Alexei Makarkin, deputy head of the Moscow-based Center for Political Technologies, said. "The tensions will remain or even escalate."