May 9 (Reuters) - A nearly week-long strike by around

3,000 U.S. Pratt & Whitney workers to keep jet engine work in

Connecticut is the latest source of uncertainty in an aerospace

supply chain already struggling to meet global demand for new

airliners.

Jeff Santini, lead negotiator for the workers, told Reuters

on Friday that the stoppage largely hinges on securing a

commitment to keep certain Pratt work for Lockheed Martin's ( LMT )

F-35 fighters in the U.S. state.

"Job security is number one right now," Santini told

Reuters, after joining federal lawmakers from Connecticut and

workers on a picket line.

On Sunday, members of the International Association of

Machinists and Aerospace Workers (IAM) rejected the company's

latest offer.

In addition to the F-35, one of the most widely used

fighters in the world, the RTX subsidiary also makes

geared turbofan (GTF) engines for European planemaker Airbus'

best-selling A320 family of jets.

Analysts warn that a lengthy strike would further strain

production. Pratt has struggled with output problems in recent

years and is searching for potentially flawed components in its

GTF engines that have grounded hundreds of planes in recent

months.

RTX has said the two sites in Connecticut remain open

despite the strike and the company has a contingency plan,

without elaborating. Pratt is telling suppliers to continue

shipping parts as usual, one of them said.

RTX said on Friday it is committed to Connecticut after

investing more than $550 million in the state since 2019.

RTX said it offered to raise wages by 10.5% over three

years, with additional cost of living and job progression

increases and a $5,000 signing bonus.

Santini said the wage increase fails to keep up with

inflation, but he has not made the union's demands public.

The strike's duration is up to Pratt, IAM International

President Brian Bryant said. "They are the ones who can very

easily get back to the table."

"It's too early to tell if the strike will impact us," an

Airbus spokesperson said by email, adding it is in close contact

with Pratt and RTX.

Lockheed Martin ( LMT ) declined to comment on Pratt work for the

F-35, which is produced at a rate of 156 fighters a year.

AeroDynamic Advisory Managing Director Richard Aboulafia

said fallout might be limited with a short strike.

"If management is smart, the strike lasts a few days,"

Aboulafia added. "If not, it lasts for months."

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