WASHINGTON, Dec 14 - U.S. lawmakers just back from a visit to Ukraine warn that Washington’s threats of sanctions and diplomatic maneuvering are not doing enough to dissuade Russian President Vladimir Putin from potentially launching an invasion, VOA reported.

The group of Democrats and Republicans visited Kyiv Saturday and Sunday where they met with the commander of the Ukrainian special forces and with U.S. special operators and National Guard troops who have been helping the Ukrainian military with training.

They described the situation as “very concerning” and urged the White House to speed up the delivery of weapons to the Ukrainian forces in the hopes of staving off a Russian invasion.

“I think promising tough action, just to be candid, after an invasion, will do very little in terms of Putin's calculus,” Republican Representative Michael Waltz told reporters Tuesday.

“We're seeing Putin, I think, do this in many respects because he knows he can get away with it,” Waltz added. “We need to help Ukraine porcupine themselves and raise the costs now.”

Democrats on the trip likewise urged the White House to take actions that will make Russia feel the blowback for an invasion of Ukraine almost instantly.

“If Putin invades, I want him to know that he'll have trouble buying a soda from a vending machine in the next five minutes, not that NATO will convene a conference to debate what to do next over the ensuing several weeks,” Representative Seth Moulton said.

“We need to clearly communicate how the weapons we provide will cause large losses of Russian troops on Day One, not just over time,” he said. “Not just convincing them or trying to convince them that an occupation will be painful, but rather that an immediate full-scale invasion will be hard to take immediately.”

The lawmakers also expressed confidence that unlike in 2014, when Russia invaded and occupied Crimea, Ukrainian forces are prepared to mount a fierce resistance if Putin sends in Russian troops. They said it would be folly, though, to think Ukrainian troops could hold out for long.

“I think what we have to work on in the immediate future, right now, is to create the capability for a strong resistance in nonconventional warfare,” said Democrat Ruben Gallego.

“(Ukraine) being able to hold out and impose costs will be very helpful,” he said. And that would “hopefully change the calculation that Putin is using.”

The lawmakers called for the White House to speed up the delivery of weapons to Ukraine, including ship-to-shore missiles, air defense missiles and additional Javelin anti-tank missiles. (voa/ez)