she says, "we can't reveal our plan, because it's secret. but with the military, we will keep this border safe." now, defending against the russian invasion, however likely, would be a tough task for ukrainian forces. tonight, international pressures mounts on vladimir putin not to strike. weijia. >> jiang: imtiaz tyab in kyiv for us, thank you. tonight, what began as a truck convoy protest in canada against vaccine mandates has snowballed into a tense international standoff. today, police moved to clear protesters from the ambassador bridge, the busiest u.s.-canada crossing, connecting detroit and windsor, ontario. tonight, cbs' kris van cleave is there. >> reporter: weijia, the ambassador bridge is responsible for one-fourth of the trade between the u.s. and canada. canada is america's largest trading partner. this is the protest that has kept that bridge shut down for six days now, something the police would like to see change. breaking down the border