Russian president Vladimir Putin has ordered "snap checks" of his country's combat readiness in the far east, Itar Tass news agency reports.
Ambassadors of European Union countries have not yet reached a decision on whether to implement new sanctions against Russia, Brussels diplomats have said.
The EU figures said that while Germany was pushing to have the sanctions implemented, several other EU countries wanted to hold off because the ceasefire in Ukraine was holding.
Countries with close ties to Russia, including Italy, Austria and Finland were said to be reluctant to implement the new sanctions.
They added, however, that the general idea was still for the sanctions to be implemented through publication in the Official Journal of the European Union on Friday.
Pro-Kiev authorities in Mariupol, a frontline city in the conflict between Ukraine and pro-Russian separatists, have announced a night curfew and other restrictions for nearby towns and villages to help control rebel movements during a fragile ceasefire.
Some locals complained that the measures - which do not apply to the city of Mariupol itself - amounted to "undeclared martial law".
Others, however, said they were a necessary step enabling Ukrainian authorities to better monitor the shaky five-day ceasefire and prevent rebels exploiting it.
One military officer told Reuters: "This is not martial law. We want them to show themselves. If someone is out there between 8pm and 6am we will know they are not civilians and we can take appropriate measures."
Russia has carried out a successful test of its new Bulava intercontinental nuclear missile and will perform two more test launches in October and November, the head of its naval forces said.
The 12-metre long Bulava, or mace, has undergone numerous tests, some of which have failed, causing setbacks for the project that aims to be the cornerstone of Russia's nuclear arsenal over the next decade.
Drones will be deployed to monitor the ceasefire in Ukraine. The chairman of the Organisation for Security and Cooperation in Europe (OSCE), Didier Burkhalter, said their drones will be sent into the field soon.
He added the organisation is also holding talks on the possibility of using national drones as soon as possible as "in-kind contribution by participating states" in the monitoring scheme.
Ukraine's President Petro Poroshenko says it is "difficult" to maintain the ceasefire because "terrorists are trying all the time to provoke" Kiev's troops.
He told a televised meeting of the government that Ukraine is "regrouping" its forces in the east of the country to defend territory, not to stage a new offensive.
He said the peace roadmap agreed last week between Ukraine and pro-Russian separatists preserves the concept of a sovereign, united Ukraine within its current borders.
Dutch Safety Board chairman Tjibbe Joustra said it will take a year to complete the report on the MH17 crash. It is at that point that investigators will be able to clarify exactly what the 'high-energy objects' that punctured the aircraft were.
Pro-Russian rebels do not have the military equipment that could be used to bring down a passenger plane such as Malaysia Airlines Flight MH17, a separatist leader has claimed.
Alexander Zakharchenko, prime minister of the self-proclaimed Donetsk People's Republic, said: "I can say only one thing: we just don't have the (military) equipment which could bring down a passenger Boeing, including this Malaysian plane."
His comments come after the release of a report by Dutch investigators suggesting MH17 was downed by a "large number of high energy objects".
Pro-Russian rebels were widely blamed for shooting down flight MH17 over eastern Ukraine in July, killing all 298 people on board.
Russian Foreign Minister Sergei Lavrov says the ceasefire in eastern Ukraine is being observed "in general" but "there are incidents when the sides blame each other".
He told a news conference today that Moscow hopes talks will soon start on the status of the Donetsk and Luhansk regions.
However, he raised concerns over the "heavy concentration" of Ukrainian troops in parts of eastern Ukraine.
Investigators believe that MH17 broke up while still in the air due to the large area covered by wreckage.
The Dutch Safety Board said: "The fact that there were many pieces of aircraft structure distributed over a large area indicated that the aircraft broke up in the air."
A total of 298 people, including 10 Britons, died in the incident in July, which came only weeks after another Malaysia Airlines Boeing 777 disappeared over the Indian Ocean.
Wreckage from the plane covered an area of approximately 10km by 5km (6 by 3 miles)