Russia has condemned the latest round of Ukraine-related sanctions imposed by the European Union, saying they endanger the fight against international terrorism.
The sanctions, announced yesterday, impose travel bans and asset freezes on 15 people, including the head of Russia's Federal Security Service and the head of the agency's department overseeing international operations and intelligence. Four members of Russia's national security council are also on the list.
A Foreign Ministry statement denounced the latest sanctions, imposed after pro-Russian rebels were suspected of shooting down an Air Malaysian plane over the Ukraine.
Russia said the sanctions show the EU is taking "a complete turn away from joint work with Russia on international and regional security, including the fight against the spread of weapons of mass destruction, terrorism (and) organised crime".
"We are sure the decisions will be greeted enthusiastically by international terrorists," the ministry said.
The response came as Russia launched artillery attacks from its soil on Ukrainian troops as it prepared to move heavier weaponry across the border, the US and Ukraine claimed.
However Russia accused Washington of lying and accused Ukraine of firing across the border on a Russian village.
It also toughened its economic measures against Ukraine by banning dairy imports.
Andriy Lysenko, a spokesman for Ukraine's national security and defence council, said five salvos of heavy rockets were fired across the border near the town of Kolesnikov in the Luhansk region in the country's east.
A border crossing point near Marynovka was fired on twice with mortars, also from the Russian side, while Ukrainian forces shot down three Russian drones, Mr Lysenko said.
If true, the allegations mean Moscow is playing a more direct role in the fighting than it has been accused of up to now - a dangerous turn in what is already the gravest crisis between Russia and the West since the end of the Cold War.
In addition, Colonel Steve Warren, a Pentagon spokesman, said the US has seen powerful rocket systems moving closer to the Ukraine border.
It was not clear what those developments mean for the international investigation into the downing of Malaysia Airlines Flight 17.
US authorities believe the separatists shot it down with a missile, perhaps in the mistaken belief it was a military plane.
A small group of Dutch and Australian investigators combed the sprawling, unsecured field where the plane came down on July 17.
They were taking notes and photos as their governments prepared police detachments they hope can protect the crash site and help bring the last of the 298 victims home.
Britain's UN Ambassador Mark Lyall Grant said the Security Council will probably endorse any agreement that Netherlands and Australia reach with Ukraine on deploying their police to the site.
It is "quite likely that the Security Council will want to take note of that agreement, very possibly in a resolution," he said, adding that he would not expect this to be controversial and it could happen very quickly.
Russia's foreign ministry responded to the US allegations about cross-border shelling by saying: "Facts and details to confirm these lying contentions do not exist."
The allegations come amid a Ukrainian government offensive against the separatists that has won back control of several important towns over the past few weeks.
Ukrainian President Petro Poroshenko told US Vice President Joe Biden in a telephone conversation that Ukrainian troops are increasingly coming under direct fire from the Russian side of the border.