July 22 (Reuters) - As the Nord Stream 2 gas pipeline nears completion, Germany has reached an agreement with the United States that it will respond to any attempt by Russia to use energy as a weapon against Ukraine or other countries in the region. The pact aims to mitigate what critics see as the strategic dangers of the $11 billion pipeline, now 98% complete, being built under the Baltic Sea to carry gas directly from Russia"s Arctic region to Germany. U.S. officials have long opposed the pipeline, which doubles the capacity of the existing Nord Stream 1 (NS 1) link. But President Joe Biden"s administration has chosen not to try to kill it with U.S. sanctions, instead persuading Berlin to agree to imposing costs on Moscow if it seeks to use the pipeline to harm Ukraine. The United States fears NS 2 increases Europe"s reliance on Russian energy, while supporters of the pipeline say Washington is seeking to increase its own liquefied natural gas (LNG) sales to the continent. Here are some significant moments in Nord Stream 2"s development: 2011 November: Gazprom (GAZP.MM) and Western partners look into expanding the pipeline system by a further 55 billion cubic metres at an estimated cost of 9.5 euros ($11.3 billion). 2015 June: Gazprom, Royal Dutch Shell (RDSa.L), E.ON (EONGn.DE), OMV (OMVV.VI), Wintershall (WINT.UL) and ENGIE (ENGIE.PA) agree to build the pipeline. 2016 March: Eight EU governments object, citing geopolitical reasons. 2017 April: Financing agreements are signed. 2018 January: Germany grants permits for construction and operation. 2019 January: The U.S. ambassador to Germany says companies could face sanctions. December: Swiss-Dutch company Allseas suspends pipe-laying. U.S. President Donald Trump signs a defence policy bill including sanctions. 2020 January: Russia targets a start in first quarter 2021. May: Germany"s energy regulator declines to grant a waiver of EU gas directives to the operators. May: An EU court throws out a challenge to EU gas rules from the operators of NS 1 and NS 2. Sept. 3: Pressure mounts on Berlin to reconsider support after the alleged nerve agent attack on Kremlin critic Alexei Navalny. Sept. 15: Data shows a Russian ship sailed for the supply base in Germany. Sept. 23: The world"s largest group of shipping insurers says it will not insure vessels involved in NS 2. Oct. 1: Denmark gives NS 2 permission to operate in Danish waters. Oct. 7: Poland fines Gazprom more than 29 billion zlotys, having launched proceedings in June. Nov. 4: Gazprom appeals in a Polish court against the fine. Nov. 28: NS 2 says it plans to resume finishing a 2.6 km stretch in German waters. Dec. 3: The United States unveils a bill targeting companies and individuals helping NS 2. Dec. 11: NS 2 says the vessel Fortuna has resumed work. Dec. 22: The Danish Maritime Authority issues notification of pipe-laying works from Jan. 15. read more Dec. 24: The Kremlin says new U.S. sanctions could complicate the completion. read more Dec. 28: NS 2 says it has completed the 2.6 km section in German waters. read more 2021 Jan 6: The northern German state of Mecklenburg-Vorpommern decides to set up a foundation to help the completion of NS 2. Jan 13: The U.S. State Department warns European companies of sanctions. Jan 14-15: NS 2 says pipe-laying will resume in Germany on Jan. 15. Uniper and Wintershall Dea say they did not receive any threats. read more Jan 20: Trump on his last full day in office imposes sanctions on Fortuna. read more Gazprom successfully places an 8-year Eurobond worth $2 billion suggesting investors see limited risks. German environmental groups file complaints with maritime regulator BSH, effectively preventing further work in Germany for now. read more Jan. 21: The European parliament passes a resolution calling for a stop to NS 2 completion in response to the arrest of Navalny in Russia. Jan. 24: Fortuna resumes work in Danish waters. read more Feb 5: Chancellor Angela Merkel says Germany is sticking with its support for the pipeline "for the time being", after condemning Russia"s expulsion of diplomats from Sweden, Germany and Poland. April 22: The U.S. Senate Foreign Relations Committee advances a bill to pressure companies helping to build NS 2. April 27: Russian vessel Akademik Cherskiy starts laying pipes for the project in Danish waters. May 19: The U.S. State Department waives sanctions around participants of Nord Stream 2, saying it was in the U.S. national interest. May 25: Merkel says she expects further discussions with the United States on the Nord Stream 2 project. read more June 1: The Kremlin says Moscow welcomes the United States" decision to refrain from sanctioning the pipeline, adding Russia does not plan to stop sending gas via Ukraine. June 4: President Vladimir Putin tells an economic forum that Russia has finished laying the first line of the pipeline to Germany. June 7: Secretary of State Antony Blinken says the completion of Nord Stream 2 is a "fait accompli", defending the U.S. decision to waive some sanctions and vowing a response if Moscow tries to use gas as a weapon. June 10: Nord Stream 2 says the project will start preparations on June 11 to fill the first of two pipelines with natural gas within a few months. June 25: German Economy Minister Peter Altmaier says he had a productive meeting with U.S. Energy Secretary Jennifer Granholm, and both countries were committed to resolving the dispute over Nord Stream 2 by the end of August. read more July 15: Biden and Merkel fail to settle their dispute over Nord Stream 2 pipeline but say they agreed Moscow must not be allowed to use energy as a weapon to coerce its neighbors. July 22: The United States and Germany announce an agreement on the Nord Stream 2 gas pipeline under which Berlin pledged to respond to any attempt by Russia to use energy as a weapon against Ukraine and other Central and Eastern European countries. Reporting by Tommy Lund and Bartosz Dabrowski in Gdansk Editing by Kirsten Donovan, Milla Nissi and Gareth Jones Our Standards: The Thomson Reuters Trust Principles.