US Senator Robert Menendez has strongly criticized Russian President Vladimir Putin’s “invasion of Ukraine,” saying he has a war against Europe. “Putin has a war against Europe being fought on Ukrainian territory. Because everything that he despises about Europe is what he's concerned about Ukraine moving towards,” he told CNN from Kiev on Sunday. “There are those in Europe and elsewhere who says, you know, we don't want to provoke Putin. Well, Putin doesn't need provocation. In this case weakness is a greater provocation for Putin act than strike,” Menendez added. The chairman of the House Foreign Relations Committee also called on President Barack Obama to take a firm stance against Moscow. "Thousands of Russian troops are here with tanks, missiles, heavy artillery, and are directly engaged in what is clearly an invasion,” the Democratic senator said. “We should be providing the Ukrainians with the type of defensive weapons that will impose a cost upon Putin for further aggression,” he added. Senator Menendez also noted that the Kremlin should pay a heavy price for its invasion of Ukraine. “If there is not a heavy price for Russia to pay for its invasion of Ukraine, then what do we say to China in the South China Sea?” he argued. European Council President Herman Van Rompuy said on Sunday the bloc's heads of state tasked their executive body to "urgently" prepare tougher economic sanctions that could be adopted within a week. Van Rompuy said the EU "stands ready to take further significant steps in light of the evolution of the situation on the ground.” The United States and the European Union have already imposed asset freezes and travel bans on senior Russian officials. In an interview with Press TV, Paul Craig Roberts, former Assistant Secretary of the US Treasury, called the 28 member-state bloc a US “puppet.” “It’s really up to Putin what happens. It’s not up to the EU. The EU is a puppet state of the United States. They’re being hurt by the sanctions that Washington has forced Europeans to impose on Russia,” he said. “The main hurt is only Europeans, not Russians.”