Poland will deploy 10,000 soldiers to help protect critical infrastructure such as railways, Defence Minister Wladyslaw Kosiniak-Kamysz said after last weekend's railway explosion, which Warsaw blames on Russia.
Earlier, Poland said it would close the last Russian consulate in its territory and urged EU allies to restrict Russian diplomats in the bloc's Schengen free-travel area in response to the blast.
Poland, a major ally in Kyiv's fight against Russia's invasion, says two Ukrainians collaborating with Moscow perpetrated the weekend blast on the Warsaw-Lublin line, which connects Warsaw to the Ukrainian border.
The pair fled to Belarus, an ally of Russia, Poland said.
Polish Foreign Minister Radoslaw Sikorski said at a news conference that the first response would be to close Russia's last operating consulate in the northern city of Gdansk. Poland has previously closed Russian consulates in Krakow and Poznan over sabotage acts.
"It was not only an act of sabotage but also an act of state terrorism," Mr Sikorski earlier told MPs of the railway attack, saying a non-diplomatic response would be coming too.
Russia denies responsibility for sabotage, citing "Russophobia" in Poland, and said it would likewise limit Poland's diplomatic and consular presence in Russia.
Mr Sikorski also told reporters he would ask other EU nations to limit Russian diplomats' travel in the 25-nation Schengen area, warning "this is not the end" of Poland's response.
"We encourage our allies in the European Union to prevent Russians from enjoying the benefits of the Schengen countries, which they are trying to destroy, among other things, by pushing migrants across the border," Mr Sikorski said.
Poland and its European Union allies accuse Belarus and Russia of orchestrating a migrant crisis on its border with Belarus.
There has been a wave of arson, sabotage and cyberattacks in Poland and other European nations since Russia's full-scale invasion of Ukraine began in 2022.
Earlier today, Romania scrambled fighter jets when a drone breached its airspace during a Russian attack on Ukrainian infrastructure near the border, the defence ministry said.
The European Union and NATO state, which shares a 650km border with Ukraine, has had Russian drone fragments fall on its territory repeatedly as Moscow attacks Ukrainian port infrastructure across the river Danube from Romania.
The ministry said the radar first picked up the signal of a drone 8km inside national airspace near the villages of Periprava and Chilia Veche in Tulcea County.
The drone signal disappeared off the radar beforere appearing intermittently for 12 minutes near villages in Galati county, it added.
Romania scrambled two Eurofighters - part of German air policing missions in Romania - and later two Romanian F-16 fighter jets and warned citizens in the southeastern counties of Tulcea and Galati to take cover, the ministry said.
The ministry added it received no reports of drones hitting ground in Romanian territory.
Poland temporarily closed Rzeszow and Lublin airports in the southeast of the country and scrambled Polish and allied aircraft as a precaution to safeguard its airspace.
