Two days after EU leaders tied Russia sanctions to respect of a ceasefire accord, Nato and the US say Russia is still “pouring” arms into Ukraine.

The allegations were made by Philip Breedlove, a US general who is Nato’s military commander, and Victoria Nuland, the US State Department’s top diplomat on Ukraine, at the Brussels Forum, an annual symposium held over the weekend.

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“We continue to see disturbing elements of air defence, command and control, resupply and equipment coming across a completely porous border”, Breedlove told the Brussels event.

Nuland said: “We have seen, month on month, more lethal weaponry of a higher calibre, of more sophistication, poured into Ukraine … the number one thing is for Russia to stop sending arms over the border so that we can have real politics, have a real ceasefire”.

The so-called Minsk ceasefire pact, agreed by the EU with Russia last month, stipulates a “pullout of all foreign armed formations, military equipment” and restoring “full control” to Ukraine of its border with Russia.

EU leaders at a summit last Thursday (19 March) decided to keep economic sanctions on Russia in place until the Minsk deal is implemented.

But they opted to legally extend the measures, which expire in July, closer to the expiration date in order to encourage Russia to fall in line.

For her part, EU foreign relations chief Federica Mogherini, who took part in the same Brussels Forum panel as Nuland, spoke in more Russia-friendly tones.

“The situation is much, much better than it used to be, not perfect yet. So you don’t have a white or black picture, you have a situation that is much better than before the meeting in Minsk … even if with some violations”, she said.

She noted that joint EU-Russia-Ukraine talks on gas and trade are “steps in the right direction”.

She also repeated the EU line that “there [is] no military means to face the crisis in Ukraine”.

Breedlove and Nuland did not rule out supply of weapons to the Ukraine military, however

“I do not think that any tool of the US or any other power should necessarily be off the table”, Breedlove said.

“We see diplomatic tools being used, informational tools being used, military tools being used, economic tools being used against Ukraine and so we in the West should consider all of our tools and apply them”.

Nuland noted: “the question becomes, if you are facing a T-90 tank with a T-72 tank, ought you to have anti-tank weapons to at least level the playing field? If you are facing Smerch artillery which can go 20 kilometres with your own local artillery, should you have some capability against that? That's the argument in favour. The argument opposed is that clearly this would constitute an escalation on the battlefield”.

“This is the [US] president's decision to make … if in fact we see a resurgence of aggression and violence that'll change the calculation”.

The Mogherini and Nuland panel at Brussels Forum also included Nato secretary general Jens Stoltenberg and Konstantin Kosachev, a Russian MP.

Kosachev claimed there are no Russian forces in Ukraine, but was contradicted by Stoltenberg, who noted that Russia itself admitted to using special forces to invade Crimea.

Kosachev prompted laughter when he asked the Nato chief: “Are you going to bomb a country which is supposed to be behind a cyber attack against a Nato member state? Are you going to bomb it? Are you going to … to start a cyber attack against this country?”.

With Russia believed to be behind a cyber attack on Estonia, a Nato member, in 2009, Nuland interjected: “Is this a planning question, Konstantin? … I think it was. Yeah. Yeah!”.

Denmark

Russia over the weekend also caused alarm by saying it will point nuclear weapons at Danish ships if Denmark hosts parts of a Nato anti-missile system.

“If that happens, Danish warships will be targets for Russian nuclear missiles”, Russia’s ambassador to Denmark, Mikhail Vanin, told Danish daily Jyllands-Posten.

A spokeswoman for Nato, which says the shield is purely defensive, said Vanin’s remarks “do not inspire confidence or contribute to predictability, peace or stability”.

Breedlove noted at the Brussels Forum, that: “Romania came under great pressure when they became a part of the [missile shield]. Poland is coming under great pressure, and now anyone else who wants to join in to this defensive capability will come under this diplomatic and political pressure”.