For Nato, its Warsaw summit may be the most crucial since Cold War where leaders will tackle challenges to search of ways to better their nations' security
US President Barack Obama has said NATO is "critical" to the security of America and its allies in Europe, a virtual rejection of Republican front-runner Donald Trump's views that the intergovernmental military alliance has outlived its utility.
The Nato warships, now under German command, will conduct reconnaissance and surveillance to help end Europe's gravest migrant crisis since World War II.
Nato head Jens Stoltenberg said on Friday that Russia's air strikes in Syria targeting rebel forces are "undermining" efforts to find a non-military solution to the war.
Afghanistan welcomed the US decision to keep thousands of troops in Afghanistan past 2016, vowing to respond to a resurgent Taliban "with full force" even as the rebels promised to wage jihad until the last American soldier leaves.
Nato secretary general Jens Stoltenberg warned that Russia is testing "some of their most modern weapons" in Syria, while carrying out a great military deployment.
Ukrainian President Petro Poroshenko on Tuesday told the country's security council that staying out of the Nato alliance was a "criminal" policy that his government is ready to reverse.
Nato on Wednesday urged Russia to withdraw all forces from eastern Ukraine and to end its support for the pro-Moscow separatists as a ceasefire appeared to unravel.
Gorbachev warned that current international efforts to solve the Ukraine crisis were "unequal to the danger that threatens us all."
Putin once again expressed his displeasure over the toppling of Ukrainian Presidential Viktor Yanukovych but offered no insight into what Russia's next actions in eastern Ukraine could be.
News agency Interfax Ukraine said the problem had occurred at bloc No 3 - a 1,000-megawatt reactor - and the resulting lack of output had worsened the power crisis in the country.
The plan will enable NATO to meet "any threats from wherever they come", Stoltenberg said.
Nearly a month after India was admitted as an observer into the mineral-rich Arctic Council, India's External Affairs Minister Salman Khurshid is visiting Norway, a member of the eight-nation forum, where he will pay a visit to the Indian research station, Himadri, in Svalbard.