Russia seized the Crimean peninsula from Ukraine in 2014 and has been accused of providing support to pro-Russian separatists in eastern Ukraine. An estimated six million Russian tourists visited the annexed Crimean peninsula over the past year — a majority of whom traveled through border crossings that were previously controlled by Ukrainian authorities — in what Ukrainian officials say is a violation of Ukrainian and international law.

Ukraine’s President Petro Poroshenko signed new legislation on Wednesday imposing jail sentences on Russians who cross the Ukrainian border illegally.

Under Ukraine's new legislation posted on Wednesday, Russian nationals will be subject to jail terms of up to eight years if they cross the Ukrainian border with fake documents or without documentation.

Current national legislation prescribes detentions of up to 15 days and imposes fines on offenders.

The new penalty applies to those who “seek to harm the interests of the state,” people banned from entry into Ukraine, as well as “representatives of military units or other law enforcement agencies of the aggressor state.”

The bill was introduced last year following the detention of two Russian Federal Security Service (FSB) border guards who reportedly got “lost” and crossed the Ukrainian border. The FSB later said they were exchanged for a pair of Ukrainian border guards who went missing in October 2017.