Newly appointed Prime Minister Liz Truss faces problems "in her in-tray" that are "arguably bigger than what Churchill faced in 1940", according to Tobias Ellwood.
Talking to GB News, the chair of the Defence Select Committee said he hoped the new Prime Minister will make a stronger statement in support of Ukraine's fight against Russia.
"If we don't put this fire out in Ukraine, it will spread elsewhere," Mr Ellwood said.
"Putin is after economic dominance. And that means more hardship here in the UK, so let's see some British leadership working with our American partners to finally stand up to what Russia is doing."
He added: "It's important that the party rallies around the new prime minister, but indeed the nation as well. This is the prime minister we are going to have for the next couple of years.
"And the problems that are in her in-tray are arguably bigger than what Churchill faced in 1940."
Mr Ellwood continued: "It is in all our collective interests to support her at this moment. We do need to move to a war-like footing."
"The appetite" to stand up against aggressors
He also highlighted how "dangerous our world is becoming" with the potential usage of nuclear weapons.
"Afghanistan was a turning point, if you like, on the world's desire, ability, appetite, to defend our international rules-based order. And the aggressors around the world are taking advantage of that.
"And my worry is, with the proliferation of weapons systems, chemical weapons and so forth, we could easily see a tactical low yield nuclear weapon being used either by a state or non-state, simply because we don't have the appetite to stand up against these nations that may eventually use one of these weapons."
Defence Secretary Ben Wallace will head to Germany this week to discuss longer-term international funding for Ukraine.
Mr Wallace recently reaffirmed the UK's leading role in training Ukrainian troops.
He revealed that now more than 4,700 soldiers have so far been trained, while the first trainers from eight partner nations have arrived and begun contributing to courses.