Wallace said, as quoted by The Sunday Times on Saturday, that a "Russian invasion" of Ukraine is "highly likely" and that Russia could "launch an offensive at any time".
The defence secretary warned that in the event of an escalation, NATO will build up its forces along the Russian borders and NATO allies will boost military spending.
"It may be that he [Russian President Vladimir Putin] just switches off his tanks and we all go home but there is a whiff of Munich in the air from some in the West," Wallace said.
The British defence secretary arrived in Moscow on Friday to meet with Russian Defence Minister Sergei Shoigu.
Wallace said the talks were "constructive and frank" and that he urged Moscow to de-escalate the situation on the Ukrainian border. Shoigu said after the talks that the level of Russian-UK relations was close to zero and that it was necessary to stop aggravating the situation in relations between Russia and NATO.
Putin Calls for 'Persistent Efforts' to Get NATO & US to Provide Legal Security Guarantees to Russia
10 February 2022, 06:18 GMT
Over the past few months, the West and Ukraine have accused Russia of a troop build-up near the Ukrainian border in alleged preparation for an "invasion". Moscow has denied these accusations, repeatedly stating that it is not threatening anyone and at the same time expressing strong concerns over NATO's military activity near the Russian borders, which it deems a threat to its national security.
Moscow has also said that Russia has the right to move troops within its national territory and warned Western countries that military deliveries to Kiev may encourage the latter to use them against the self-proclaimed republics in the southeast of Ukraine (Donbass).