Jeb Bush said that Russia must respect the sovereignty of all its neighbors. The former Florida governor was speaking in Berlin during the beginning of his five-day European tour.

Bush, who is on the verge of entering the 2016 presidential campaign, spoke to German business leaders and politicians. However, it was Russian President Vladimir Putin whom he targeted in his speech.

“Who can doubt that Russia will do what it pleases if its aggression goes unanswered?” the Los Angeles Times quoted Bush. “Our alliance, our solidarity and our actions are essential if we want to preserve the fundamental principles of our international order … an order that free nations have sacrificed so much to build.” Bush’s comment comes as G7 countries agree to impose more sanctions on Russia, if required, so that the political conflict in eastern Ukraine can be settled.

Bush’s visit to Germany has been questioned by opposition politicians in the country. Some of them believe it may be seen as an endorsement of a probable presidential candidate of another country.

Opposition MP Jürgen Trittin said he was “amazed” how the German government had welcomed the U.S. politician. Josef Janning, a senior policy fellow at the European Council on Foreign Relations, said the meetings had displayed Bush’s international capabilities as a politician.

Bush is expected to announce his presidential campaign on Monday. He is likely to promote a foreign policy based on strong defense and alliances.

Bush has two former U.S. presidents in his family. The Wall Street Journal reports that his father, George H.W. Bush, is regarded highly in Germany for being one of the key figures in the reunification of East and West Germany. His brother George W. Bush, on the contrary, is quite unaccepted in the country due to his role in Afghanistan and Iraq during his presidency.

Germany may not be deeply interested in Jeb Bush at the moment. According to Josef Braml, Germany is interested in U.S. foreign policy. But the expert on transatlantic affairs at the German Council on Foreign Relations said that it was Hillary Clinton, not Bush, who had been “the face of U.S. foreign policy” for a while.