BERLIN, Dec 12 (Reuters) - German Chancellor Olaf Scholz is in Warsaw on Sunday for talks on the migrant crisis at the Polish-Belarusian border, Poland"s row with the EU over judicial independence, tensions with Russia over its military build-up near Ukraine and the fate of a Russian gas pipeline to Germany. The two neighbours have been clear about what they expect from each other. Polish Prime Minister Mateusz Morawiecki has said he would urge Scholz to oppose the start-up of the Nord Stream 2 pipeline to bring Russian gas to Germany, bypassing Ukraine, as it could be used by Russia"s President Vladimir Putin against Europe. Germany has backed Poland"s efforts to stop the flow of migrants seeking entry from Belarus, a crisis the European Union has accused Minsk of engineering, and said it would help Warsaw and Brussels find a solution to their legal dispute. Yet Germany"s new government has not made a public commitment that it would halt the Nord Stream 2 pipeline if Russia were to invade Ukraine, as demanded by Poland and the United States. Russia has been amassing troops on its border with Ukraine, sparking fears of a possible invasion. U.S. President Joe Biden warned Putin on Tuesday that Nord Stream 2 could be disrupted and tough economic sanctions put in place if troops invade. U.S. officials have told members of Congress they have an understanding with Germany about shutting down the Nord Stream 2 pipeline if Russia invades Ukraine, a senior congressional aide said on Tuesday. German officials have not confirmed those reports but Scholz said on Wednesday that there would be consequences if Russia breached Ukraine"s border. German Foreign Minister Annalena Baerbock struck a reconciliatory tone on Poland"s legal dispute with Brussels during a visit to Warsaw on Friday, saying that Germany would help find a solution. The European Court of Justice has imposed fines on Poland after it found that judicial reforms passed by the right-wing Law and Justice (PiS) party breached EU law. Poland has refused to pay the fine and its own top court has ruled that Polish law can take precedence over EU rules.