Tensions are mounting in the Ukraine conflict.

American Foreign Minister Antony Blinken accused Russia on Wednesday of planning "substantial aggressive steps against Ukraine". There is "evidence" of these plans, Blinken said on Wednesday after a meeting of NATO foreign ministers in Riga, Latvia.

He threatened Moscow with severe economic sanctions in the event of an attack.

Blinkens' meeting with Russian Foreign Minister Sergei Lavrov was planned for Thursday.

Russian plans ranged from "efforts to destabilize Ukraine from within to large-scale military operations," Blinken said. "We don't know whether President (Vladimir) Putin made the decision to invade. We do know that he creates the conditions to do this in a short time, should he decide to do so. "

Blinken said it had "made it clear to the Kremlin that we would react decisively". This also included "a number of effective economic measures that we have so far refrained from in the past."

The NATO allies would also "ensure that Ukraine has the means to defend itself".

At the end of the meeting in Riga, NATO Secretary General Jens Stoltenberg said that NATO had a "wide range of options" for reacting to a possible attack by Russia on Ukraine. He mentioned above all economic and financial sanctions on the individual member states. 

At the same time, Stoltenberg referred to NATO's reaction to the Russian annexation of the Ukrainian Black Sea peninsula of Crimea in 2014 and the fighting in eastern Ukraine. This had "led to the greatest reinforcement of our collective defense since the end of the Cold War," emphasized Stoltenberg. At that time, the Alliance stationed "combat-ready units" in Poland and the Baltic states, increased their presence in the Black Sea and increased air surveillance. Stoltenberg reiterated that Russia had "no veto" on a possible accession of Ukraine to NATO.

According to the Ukrainian government, Russia has deployed troops, tanks and other heavy equipment on the border with Ukraine for the second time this year.

The West fears that the situation of 2014 could repeat itself when Russia annexed Crimea.

Moscow denies any warlike intent.