Sen. Jim Inhofe, R-Okla., said Monday that the U.S. should send more NATO forces into the Black Sea if Russian President Vladimir Putin does not back off a naval confrontation with Ukraine.

More sanctions and arms sales to Ukraine may also be needed because Putin is “not serious about peace” and seeks only to advance his power in the region, Inhofe, who is the Senate Armed Services Committee chairman, said in a statement.

"The United States, with our European allies, must take action to reinforce our commitment to Ukraine's sovereignty and restoration of its territorial integrity,” Inhofe said. "If Putin continues his Black Sea bullying, the United States and Europe must consider imposing additional sanctions on Russia, inserting a greater U.S. and NATO presence in the Black Sea region and increasing military assistance for Ukraine."

Russia fired on three Ukrainian vessels on Sunday as they sailed near Crimea, which Moscow annexed over international outcry in 2014. The clash wounded Ukrainian sailors and Russia impounded the ships.

Tensions escalated on Monday when Ukraine’s parliament voted to impose 30 days of martial law beginning on Wednesday and the U.S. along with other allies decried Moscow’s actions during an emergency meeting of the United Nations Security Council.

"Russia's latest provocations against Ukraine are also a reminder that strategic competition with Russia and China, as highlighted by [Defense Secretary Jim] Mattis, is an immediate and urgent reality,” Inhofe said. “These authoritarian powers will continue to test the limits of American resolve as they seek to advance their dark view of the world.”

Putin has been supporting separatists in the eastern part of Ukraine for years. Ukraine, a former Soviet republic, has been leaning toward the West in recent years and began receiving Javelin anti-tank missiles from the U.S. earlier this year.