Poland, Estonia, Latvia, and Lithuania called on the European Union to build a line of defense along the bloc's border with Russia and Belarus to protect the EU from military threats and other harmful actions from Moscow.
The leaders of the four countries, which each share a border with either Russia or Belarus, drafted a letter to the EU President detailing the scale and cost of the project. EU countries would be required to commit political and financial support.
"The creation of a system of defense infrastructure along the external border of the EU with Russia and Belarus will meet the acute and urgent need to protect the EU from military and hybrid threats," the letter reads.
Western intelligence officials have reportedly warned about increasing Russian sabotage operations across Europe.
The letter also suggests that the defense line could be constructed in coordination with NATO and its military requirements.
Some EU officials estimate the cost of building this defense line along the EU's 700-kilometer border with Russia and Belarus to be around 2.5 billion euros ($2.67 billion).
U.S. and allied intelligence officials have observed an increase in low-level sabotage operations in Europe, which appear to be part of Russia's strategy to undermine support for Ukraine.