The Russian miliatry build at the border with Ukraine brings back 'dark' memories, according to European Union High Representative Josep Borrell.

Concerns have been growing about a potential invasion by Russia - after an estimated 100,000 troops started gathering near the border. 

In a press conference, following a day of discussions, Mr Borrell said EU nations and allies had reaffirmed full and unquestionable support to Ukraine. 

Any military aggression would have 'consequences and costs to the perpetrator', Mr Borrell said. 

Russia has consistently denied it is planning to invade Ukraine. The Kremlin has also accused the West of escalating tensions after the NATO alliance announced its members had placed troops on standby. 

A number of nations have made the decision to move military hardware to Baltic nations. Denmark will bolster a NATO air policing mission by sending four fighter jets to Lithuania, while Spain is said to be considering sending fighter jets to Bulgaria. 

NATO Secretary General Jens Stoltenberg said, "We will always respond to any deterioration of our security environment, including through strengthening our collective defence."

Just hours after the U.S. announced it was advising families of diplomats based in Ukraine to leave the country, U.S. Secretary of State Antony Blinken briefed EU officials in what was described as an 'informal exchange on the security situation'.

European Union officials have been keen to stress that any aggression towards Ukraine will be met with a severe response from the West. 

A $1.36bn financial support package is also being offered to Ukraine, with EU President, Ursula von der Leyen saying it will be used to help Ukraine 'address its financing needs due to conflict'.

Ukraine's President, Volodymyr Zelensky welcomed the financial support, writing on Twitter that a "strong Ukraine is key for European security."

For now, officials say they will continue to encourage dialogue and engagement - but should diplomacy fail, EU High Representative Josep Borrell said member states are well advanced in the preparation of responses to Russian aggression. 

It's also believed a decision could soon be made on whether an EU assistance mission will be launched in Ukraine to support military training.

Cover image: Russian troops target a mortar during drills at the Kuzminsky range in the southern Rostov region, Russia on January 21. Reuters/Sergey Pivovarov