Republican Reps. Mike Rogers and Mike Turner are urging U.S. President Joe Biden to further arm Ukraine and “deploy a U.S. military presence in the Black Sea” to warn off a renewed invasion threat from Russian forces.

“With the recent massing of Russian forces on the Ukrainian border, we urge your administration to take immediate and swift action to provide support to Ukraine in the form of intelligence and weapons,” Rogers, of Alabama, and Turner, of Ohio, said Friday in a letter to Biden, which was obtained by Defense News. Rogers and Turner are the ranking members of, respectively, the House Armed Services Committee and Strategic Forces Subcommittee.

“We also urge your administration to deploy a U.S. military presence in the Black Sea to deter a Russian invasion,” the letter says, adding Biden’s administration “cannot ignore Russia’s continued threat to international law and Ukraine’s territorial sovereignty.”

“Additionally, we urge you to immediately consider an appropriate U.S. military presence and posture in the region and to initiate appropriate intelligence sharing activities between the U.S. and Ukraine to prevent the situation from escalating further.”

The call comes as Ukraine’s defense ministry said Wednesday there are 90,000 Russian troops not far from the border and in rebel-controlled areas in Ukraine’s east. Satellite images showed a buildup of armored units, tanks and self-propelled artillery as well.

“Russia has periodically deployed and built up troops to maintain tensions in the region and exert political pressure on neighboring countries,” the ministry said.

Ukraine and Romania told Congress last week Western allies should step up their military presence in the Black Sea to counter Russia’s militarization of the region. Ukraine said it wants Washington’s backing for a NATO force on the Black Sea akin to its Baltic Sea force, which has multinational battalion-size battlegroups.

Russia has cast its weight behind a separatist insurgency in Ukraine’s east that erupted shortly after Moscow’s 2014 annexation of Ukraine’s Crimean Peninsula and has left more than 14,000 people dead. Russia has repeatedly denied any presence of its troops in eastern Ukraine.

Several Republican lawmakers, including the Senate Armed Services Committee’s ranking member, Sen. Jim Inhofe, R-Okla., have posted on social media lamenting the new massing of troops and suggesting the Biden administration act.