U.S. President-elect Donald Trump's optimism to have better ties with Russia has raised concerns of a greater conflict with Moscow's rivals. The relationship between Trump and Russian President Vladimir Putin has given rise to speculation of a war in Ukraine, according to reports.

Last week, Ukrainian politician and former prisoner of war Nadiya Savchenko appealed to Trump to toughen sanctions against Moscow. Savchenko is a former fighter pilot in the Ukrainian ground forces who was captured by a pro-Russian militia in 2014 in eastern Ukraine and handed over to Russia.

"I’d like to attract your attention to the problem of international support and protection of territorial integrity of Ukraine inasmuch as the United States of America as a state is ahead of protecting Western-European Values in the world and always gave the support for the Ukrainian people in their aspiration to joint the family of the countries that stick to the democratic values, inviolability of frontiers, law supremacy," Savchenko wrote in a Facebook post.

"Ukraine suffers from Russian Federation aggression, it has lost part of its territory, ten thousands of its soldiers, volunteers, civilians have been killed on the battle-field, a great number of Ukrainian hostages are illegally detained in the prisons and are subjected to tortures by the Russian Federation," she added.

Russia's Deputy Foreign Minister Sergei Ryabkov also told Interfax news agency last week that there were contacts between Russia and "influential people" in Trump's circle prior to the U.S. presidential election.

Viktor Kremeniuk , deputy director of the official Institute of USA-Canada Studies in Moscow, reportedly said: “Everyone seems to be playing the Russian card these days, trying to boost their own internal unity by focusing blame on Russia,” adding: “They believe that we are causing problems for them, and there’s no way we can disprove that we are doing it. These accusations have a life of their own, they drive tensions up and trust down, and it just gets worse and worse.”

While tensions between the U.S. and Russia remain, Putin was cautiously optimistic after Trump's win.

“We heard [Trump’s] campaign rhetoric while still a candidate for the U.S. presidency, which was focused on restoring the relations between Russia and the United States,” Putin said. “We understand and are aware that it will be a difficult path in the light of the degradation in which, unfortunately, the relationship between Russia and the U.S. are at the moment.”