The European Union estimates that 150,000 Russian forces have already gathered for the largest military mobilisation ever along Ukraine’s borders, and that a clash would only take “a spark.”

Simultaneously, EU foreign policy chief Josep Borrell said Monday that incarcerated Russian opposition leader Alexei Navalny’s health and welfare were “important,” and that the 27-nation party would keep the Kremlin responsible for his health and safety.

Despite the troubling events, Borrell said after a virtual meeting of EU foreign ministers that “for the time being, there is no change in the direction of more sanctions” to be imposed on Russia.

He also mentioned that there was no call for a coordinated EU diplomatic action of expulsions in the standoff between EU member state the Czech Republic and Russia in the aftermath of Prague’s allegation that Moscow was involved in a 2014 ammunition depot blast.

The massing of Russian forces, including military field hospitals, and “all forms of warfare” became more risky at this time, according to Borrell.

“This is the largest military operation of the Russian army on Ukrainian borders in history. When you send a large number of soldiers, it is obvious that there is cause for concern,” Borrell added. “Well, a spark will go here and there.”

Borrell refused to say where he got the number of 150,000 Russian troops. However, it is higher than the 110,000 figure provided by Ukrainian Defense Minister Andriy Taran on Wednesday.

More than 14,000 people have died in seven years of combat in eastern Ukraine between Ukrainian forces and Russia-backed separatists, which exploded after Russia’s annexation of Ukraine’s Crimean Peninsula in 2014. The EU has been adamantly opposed to the annexation but has been unable to save it.

Efforts to find a diplomatic solution have failed, and breaches of a precarious ceasefire have become more common in recent weeks across Ukraine’s eastern manufacturing heartland, known as the Donbas.

Diplomats had anticipated that there will be no risk of fresh sanctions being imposed on Moscow right away, but they would now aim to exert more leverage through diplomacy.

Moreover, French President Emmanuel Macron said over the weekend that, while dialogue with Russia is necessary, “clear red lines” with potential sanctions must also be drawn with Moscow over Ukraine.

“Overall, relations with Russia are not improving; on the contrary, tensions are rising on several fronts,” Borrell said.

“We demand that Russia withdraw its troops,” Borrell said.