(Reuters) -The European Commission on Monday approved U.S. Steel's $14.9 billion buyout by Japan's Nippon Steel, allaying competition worries, even as the deal faces regulatory scrutiny and political opposition in the U.S.

The deal, however, has been opposed by several U.S. lawmakers on national security grounds. It faces scrutiny from antitrust regulators and has drawn criticism from the powerful United Steelworkers union.

Here's a timeline of recent events leading up to the deal between Japan's largest steelmaker and the company whose steel was used to build iconic structures such as the United Nations building in New York City and the New Orleans Superdome.

DATE DEVELOPMENT

Aug. 13, U.S. Steel announces its aim to explore

2023 strategic options after receiving

unsolicited bids, ranging from the

acquisition of certain production assets to

consideration for the entire company

Aug. 13, U.S. Steel rejects a $7.3-billion offer from

2023 Cleveland-Cliffs, leading to the start of a

formal review of its strategic options

Aug. 14, The United Steelworkers (USW) union supports

2023 Cleveland-Cliffs' bid to acquire U.S. Steel,

saying the company is the best strategic

buyer

Aug. 14, Shares of U.S. Steel rise after privately

2023 held firm Esmark makes a $7.8-billion

all-cash offer for the company

Aug. 16, ArcelorMittal, the world's second-largest

2023 steelmaker, considers a potential offer for

U.S. Steel, Reuters reports

Aug. 17, U.S. Senator J.D. Vance asks U.S. Steel to

2023 rule out a foreign buyer for the company

Aug. 17, U.S. Steel states that its labor agreement

2023 with USW does not grant the union the right

to veto a potential sale of the company

Aug. 22, Cleveland-Cliffs demands U.S. Steel reveal

2023 all buyout offers it has received

Aug. 23, Esmark withdraws its bid for U.S. Steel,

2023 respecting the position of the USW union,

which supports Cleveland-Cliffs' offer

Aug. 29, U.S. Steel begins the due-diligence process

2023 after entering agreements with numerous

third parties

Sept. 20, U.S. Steel and Cleveland-Cliffs clash over a

2023 confidentiality pact

Sept. 21, Canada's Stelco Holdings considers a bid for

2023 U.S. Steel, Bloomberg news reports

Sept. 28, U.S. Steel allows Cleveland-Cliffs to

2023 participate in its sale process

Oct. 31, Major automakers oppose Cleveland-Cliffs'

2023 proposed acquisition of U.S. Steel, citing

potential cost increases and a slowdown in

electric-vehicle sales

Dec. 18, Japan's Nippon Steel announces its plan to

2023 buy U.S. Steel in a deal valued at $14.9

billion

Dec. 19, Three U.S. Republican senators urged

2023 Treasury Secretary Janet Yellen to block the

deal for U.S. Steel by Nippon Steel, citing

national security concerns.

Dec. 20, Brian Deese, a key player in President Joe

2023 Biden's 2024 re-election bid, said Nippon's

proposed purchase of U.S. Steel was

concerning and that the administration

should look closely at it.

Dec. 21, The White House said Nippon Steel's proposed

2023 acquisition of U.S. Steel deserves "serious

scrutiny," given the company's core role in

U.S. steel production that is critical to

national security.

Dec. 22, Japanese Industry Minister Ken Saito said

2023 that U.S.-Japanese ties were "stronger than

ever," although he declined to comment

directly on growing scrutiny in the United

States of a proposed deal for Nippon Steel

to buy U.S. Steel.

Jan. 05, Nippon Steel was confident of successfully

2024 completing its planned acquisition of U.S.

Steel, despite opposition from labor union

and certain U.S. senators, its president

said.

Jan. 12, Nippon Steel said President Eiji Hashimoto

2024 would become CEO and chairman effective

April 1, remaining at the helm as the top

Japanese steelmaker aims to complete a deal

to take over U.S. Steel

Jan. 24, Nippon Steel Executive Vice President

2024 Takahiro Mori met U.S. Congress members to

discuss acquisition of U.S. Steel, as it

faced strong resistance to the deal.

Jan. 30, Sumitomo Mitsui Financial Group, Mitsubishi

2024 UFJ Financial Group and Mizuho Financial

Group planned to lend Nippon Steel a

combined $16 billion for its planned

acquisition of U.S. Steel.

Feb. 07, Nippon Steel said it was on track to

2024 finalize its planned acquisition of U.S.

Steel by the end of September as it stepped

up talks with key stakeholders, particularly

labor unions.

March 04, A senior Nippon Steel executive told Reuters

2024 he was set to meet the United Steelworkers

union chief to seek support for acquiring

U.S. Steel.

March 13, President Joe Biden planned to express

2024 concern over Nippon Steel's proposed

purchase of U.S. Steel, pushing the U.S.

company's stock nearly 13% lower on bets the

deal could face greater political

opposition.

April 10, The U.S. Department of Justice opened an

2024 in-depth antitrust investigation into Nippon

Steel's takeover of U.S. Steel.

April 12, U.S. Steel shareholders voted to approve the

2024 acquisition, taking the merger one step

closer to completion even as political

opposition to the deal mounts.

April 17, President Joe Biden said at an event in

2024 Pittsburgh that the U.S. Steel should stay a

U.S.-owned company.

May 2, 2024 The U.S. Department of Justice sent a

"second request" to U.S. Steel, seeking more

details and documentary materials as part of

an antitrust review of the deal.

May 6, 2024 The European Commission approved U.S.

Steel's $14.9 billion buyout saying that the

deal does not raise competition concerns.

Sources: Reuters reports, company records

(Reporting by Abhinav Parmar, Shivansh Tiwary, Kannaki Deka and Aatreyee Dasgupta, Pratyush Thakur; Editing by Anil D'Silva, Maju Samuel and Arun Koyyur)