U.S. senators John McCain, Kelly Ayotte and Lindsey Graham during a press conference on Capitol Hill in Washington, DC, in 2016 | Jim Watson/AFP via Getty Images US senators praise Ukrainian marines, slam Putin ‘I admire the fact that you will fight for your homeland,’ Lindsey Graham tells Ukrainian soldiers.

On the frontline of the war in Ukraine, U.S. Senators John McCain and Lindsey Graham voiced strong support for Ukrainian marines and sharply criticized Russian President Vladimir Putin, underscoring the gulf between leading Republicans in Congress and President-elect Donald Trump over Russia policy.

“I admire the fact that you will fight for your homeland,” Graham told Ukraine’s 36th Separate Marine Brigade in the town of Shyrokyne, about four kilometers from the line of contact, according to a video released Monday by the Ukrainian presidency.

“Your fight is our fight,” Graham said during the visit on Saturday alongside President Petro Poroshenko. “2017 will be the year of offense,” he continued. “All of us will go back to Washington and we will push the case against Russia. Enough of a Russian aggression. It is time for them to pay a heavier price. Our fight is not with the Russian people but with Putin. Our promise to you is to take your cause to Washington, inform the American people of your bravery and make the case against Putin to the world.”

McCain, a former Republican presidential candidate and prisoner of war in Vietnam, said: “I believe you will win. I am convinced you will win and we will do everything we can to provide you with what you need to win. We have succeeded not because of equipment but because of your courage. So I thank you and the world is watching and the world is watching because we cannot allow Vladimir Putin to succeed here because if he succeeds here, he will succeed in other countries.”

Graham, McCain and Senator Amy Klobuchar, a Democrat from Minnesota, traveled throughout the former Soviet Union in recent days in an effort to reassure U.S. allies, particularly in the Baltics, that Congress remained committed to NATO and to protecting members of the Transatlantic alliance from Russian aggression.

Shyrokyne, a village just east of the strategic port city of Mariupol on the Azov Sea, was largely destroyed in fierce fighting during the first half of 2015 and is crucial to Ukraine's continued effort to defend against a potential invasion.

A peace agreement brokered by Germany and France, called the Minsk 2 accord, has never been implemented and, though fighting and casualties have subsided, clashes continue on a constant basis.

On Saturday, as the senators were visiting, the Ukrainian military said there were at least 20 incidents of hostile fire, including attacks by grenade launchers and sniper rifles. The three American senators were each given fragments of an artillery shell as a souvenir of their visit, a spokesman for the Ukrainian presidential administration said.

Meanwhile, the standoff in eastern Ukraine has become a frozen conflict, with the disputed regions of Donetsk and Luhansk forming another of the gray buffer zones that Russia has used to destabilize countries that were once part of the Soviet Union but have sought to escape the Kremlin’s grip.

The appearances by the three American senators highlighted the obstacles Trump will face should he try to ease pressure on Russia any time soon.

Similar zones exist in Abkhazia and South Ossetia, the disputed regions of Georgia, and in Transnistria, a disputed region of Moldova.

In the conflict zone, everyday transactions are conducted in Russian rubles rather than Ukrainian hryvnia, and most goods are trucked in across the border from Russia. Residents of the conflict zone must pass through military checkpoints in order to enter territory still controlled by the Ukrainian government in order to reach banks where they can access savings, collect pensions and carry out any other business with the Ukrainian authorities.

Trump has expressed a desire to improve relations with Russia and praised Putin’s decision last week not to respond to a new round of sanctions imposed by the Obama administration over Russia’s alleged computer hacking and interference in the U.S. presidential election.

The appearances by the three American senators, and their sharp criticism of Putin, highlighted the obstacles Trump will face should he try to ease pressure on Russia any time soon. Most Republican lawmakers in the U.S. have called for a thorough investigation of the hacking, and there is broad bipartisan support in Congress for Ukraine, particularly in response to Russia’s invasion and annexation of Crimea in 2014.