Relations between East and West remained strained over Ukraine, as President Obama signed a bill providing the country with 1 billion in US loan guarantees as well as sanctions on Russians on Thursday.

Over in Lithuania, Nato jets took part in an air patrol which acted to reassure its Eastern European members, and halted military and civilian cooperation with Russia in response to its annexation of Crimea.

Nato Deputy Secretary General Alexander Vershbow explained the organisation’s actions:

“A key part of the NATO response to the crisis with Russia over Ukraine is to strengthen deterrents and visible assurance for our allies on the front lines. So, I am very pleased to be able to see this kind of visible assurance and deterrents in action here, in Siauliai airbase.

Nato has expressed fears that the build-up of Russian troops along Ukraine’s eastern border could lead to an invasion. But Russian foreign Minister Sergei Lavrov questioned Nato’s own military movements:

“Our stand is that Russian-NATO relations are also regulated by certain rules, including the Rome declaration, and the basic agreement of the NATO-Russia Council, according to which, there must be no additional constant military presence on Eastern European territory.”

In another development, Ukraine has accused Russia of having a hand in the sniper attack which killed 76 people during protests in Kyiv in February.

However, the Russian Foreign Minister says he has a huge amount of evidence which contradicts these claims.