(Reuters) – German Chancellor Olaf Scholz halted certification of the Nord Stream 2 gas pipeline designed to boost Russian gas supply to Germany on Tuesday after Russia formally recognised two regions in eastern Ukraine as independent.

Here are significant events in the development of Nord Stream 2 (in chronological order):

2011

November: Gazprom and Western partners look into building a second 55 billion cubic metre twin pipeline across the Baltic Sea between Russia and Germany with an initial estimated cost of 9.5 billion euros ($11.3 billion).

2015

June: Gazprom, Royal Dutch Shell, E.ON, OMV, Wintershall and Engie agree to build the pipeline.

2016

March: Eight EU governments object to the plan on political grounds.

2017April: Financing agreements are signed.

2018

January: Germany grants permits for construction and operation.

2019

January: The U.S. ambassador to Germany says companies involved in the project could face sanctions.

December: Swiss-Dutch company Allseas suspends pipe-laying.

U.S. President Donald Trump signs a defence policy bill including sanctions.

2020

May: Germany’s energy regulator declines to grant a waiver of EU rules demanding gas suppliers and operators of pipelines be separately owned, while an EU court throws out a challenge to that rule.

Sept. 3: Pressure mounts on Berlin to reconsider support after the alleged nerve agent attack on Kremlin critic Alexei Navalny.

Sept. 23: The world’s largest group of shipping insurers says it will not insure vessels involved in the project.

Oct. 1: The project wins permission to operate in Danish waters.

Dec. 3: The United States announces a bill targeting companies and individuals helping the project.

Dec. 28: The 2.6 km section of the pipeline in German waters is completed.

2021

Jan 20: Trump on his last full day in office imposes sanctions on Russian pipe-laying ship Fortuna.

German environmental groups file complaints with maritime regulator BSH , effectively preventing further work in Germany.

Jan. 21: The European Parliament passes a resolution calling for a stop to the pipeline’s completion in response to the arrest of Navalny in Russia.

Jan. 24: Fortuna resumes work in Danish waters .

April 22: The U.S. Senate Foreign Relations Committee advances a bill to pressure companies helping to build the pipeline.

May 19: The U.S. State Department waives sanctions on participants of Nord Stream 2, saying it was in the U.S. national interest.

June 4: President Vladimir Putin says Russia has finished laying the first line of the pipeline to Germany.

June 7: U.S. Secretary of State Antony Blinken says 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 to fill the first of two pipelines with natural gas within a few months.

July 22: The United States and Germany announce an agreement on Nord Stream 2 under which Berlin also pledged to respond to any attempt by Russia to use energy as a weapon against Ukraine and other central and eastern European countries.

Aug 20: The Biden administration imposes sanctions on a Russian ship and two companies involved in the pipeline.

Putin says there are 15 km (9 miles) left to finish NS 2.

Aug 25: Duesseldorf Higher Regional Court rules that Nord Stream 2 is not exempt from EU rules requiring separate ownership of gas suppliers and pipeline operators.

Sept 10: Gazprom says it has completed construction of the pipeline.

Sept 13: Germany’s energy regulator says it has four months to complete certification of the piepline.

Oct 4: Nord Stream 2 starts filling one of its two pipelines with gas for tests.

Oct 5: Nord Stream 2 says it has appealed a court decision that confirmed the pipeline will not be exempt from EU rules that require the owners of pipelines to be different from the gas suppliers.

Nov 15: Germany’s energy regulator said Ukrainian gas companies Naftogaz and GTSOU were given notice that they would be included in the German certification process.

Nov 16: Germany’s energy regulator said the certification process for NS2 was suspended.

2022:

Jan. 14: The U.S. Senate fails to pass a bill sponsored by Republican Senator Ted Cruz to impose sanctions on Nord Stream 2 a day after the Democrats unveiled their own legislation.

Feb. 22: German Chancellor Olaf Scholz halts certification of the pipeline after Russia formally recognised two regions in eastern Ukraine as independent.

(Reporting by Tommy Lund and Bartosz Dabrowski in Gdansk and Nina Chestney in London; editing by Jason Neely)

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