The European Union will respond to future provocations by Russia, according to the bloc's foreign affairs chief.
Josep Borrell was speaking during a debate on Russia in the European Parliament on Wednesday, where he told MEPs that Brussels won't accept further intimidation by Moscow.
"We don't want to feed a dynamic of escalation - let that be clear. We nevertheless are showing that we will not accept intimidatory tactics and that we will have to respond to them if they happen," Borrell told European lawmakers.
He also said that relations between Europe and Russia are at a "low point".
The Spaniard's words come as diplomats from Slovakia and the three Baltic countries were given one week to leave Russia.
The expulsions come as a retaliatory move by the Kremlin, after the four countries kicked out seven Russian diplomats last week, in "solidarity" with the Czech Republic.
Prague has accused Moscow of being behind a 2014 explosion at one of their ammunition depots, adding to the long list of differences between Europe and Russia.
But Katalin Cseh, an MEP with the Renew Europe Group, told Euronews that Europe needs to do more than just expel diplomats.
"I believe that the EU has to do much more. This is why we put pressure on High Representative Borrell to put sanctions on Russian diplomats stationed in Brussels and also on the German government to stop the construction of the pipeline. We have to treat Russian aggression as it is as a threat, and we should not stay silent any longer," the Hungarian said.
She added: "We have to be more assertive and we have to sanction oligarchs and human rights violators with our methods."
While most MEPs agree that the EU must take a tougher line against the Kremlin, communication channels must still remain open, according to Slovak MEP Vladimír Bilčík.
"We need to have a good partnership with Russia. We need to have a good dialogue with Russia, but with clear red lines, defending our interests, our values and our security."
Despite there still being unresolved issues over Ukraine and Kremlin critic Alexei Navalny, Borrell did leave the door open to dialogue with Russia, saying the two must continue to engage on the biggest issues, including climate change.